freeze interview questions

Top freeze frequently asked interview questions

Why do damaged hard drives freeze the entire system?

Why does a hard drive which is known to have bad blocks (verified in HDTune and HDDScan), freezes down my entire system?

It is not the OS drive; it is attached to another SATA port, and I'm trying to copy files from it to another healthy drive.

I have experienced this issue with almost every damaged hard drive and every Windows PC.

I would expect to see freezing only for the program I'm using to copy the files (Windows Explorer, etc.), but instead my entire PC gets jerky, and I cannot browse web or watch movies while copying files from the damaged drive.

The long story.

I live in a rural area where there are problems with electricity (brownouts, etc.). I myself am using a UPS and my own hard drives are perfectly fine. But my neighbors often ask for help with their PC issues, and I often find that their hard drives are damaged, most probably because of electricity issues. Of course, after replacing the damaged drive I suggest my neighbors to buy an UPS.

I have always wondered, why my PC freezes entirely while retrieving data from damaged drives. Is it a hardware issue? Is it caused by the way OS reads data? Is it something Windows-specific, and I won't experience it on *nix?

Anyway, from now on I will use some dedicated software (such as Roadkil's Unstoppable Copier) instead of Windows Explorer, although I'm not sure if this will work differently, without freezing entire PC.

It is not a request for help, it is more for educational purposes, so I know why the things work that way.

Source: (StackOverflow)

How do I troubleshoot a Windows 7 freeze or slowness? [duplicate]

Possible Duplicate:
What are the first steps for diagnosing a slow machine?

I have a new pc with windows 7 which freezes randomly. I hit every single key on the keyboard and it works again. Is there a way to prevent windows 7 from freezing?

Source: (StackOverflow)

Hung process in Windows: Is there any way to see why?

I tried to print a doc in word, and word froze. Is there any way for me to see what resource it's waiting for?

I'm using windows XP and word 2007 (though I imagine the answer doesn't depend on the process that froze)

Source: (StackOverflow)

Installer hangs on "waiting for other installations to finish" despite no other installations in progress

I started an installation of the Xcode 4 developer's preview last night before going to bed. When I woke up, the installation had popped up a message saying to close Xcode first (doh!). I did so, but whatever script had displayed the message seemed to have hung because the (uncancellable) message wouldn't disappear, and the installer wouldn't progress.

After force quitting the Installer app, the message above was still showing, so I restarted my MacBook Pro and then tried the installation again. This time it wouldn't even start, instead showing one of those candy-stripe activity bars and the message:

Waiting for other installations to finish

At this point, I'm stumped. There are no other installations in progress, so there must be some artifact left over from the interrupted install that's gumming up the works. But what?

Source: (StackOverflow)

Windows 10 equivalent to 'explorer.exe'

I am an early adopter of Windows 10, and I am a .NET / Web developer so I like to push the bounds a bit when testing out a new OS. I also try to work against the latest / freshest builds available.

With prior releases of windows, when the Windows button and taskbar became unresponsive you could kill the explorer.exe process in Task Manager.

With Windows 10 (RC), the game has changed a bit. Anyone know how to reset the explorer.exe process?

How can I recover when the OS is hung up and the start button is unresponsive.

I'd prefer not to (a) log out or (b) restart.

This is more of a curiosity than a REAL problem, but thanks in advance!


The new task manager doesn't show process names, and there is an application called "Windows Explorer" but I think its limited to the actual file browser (Explorer) and restarting it has no effect on the start menu.

Source: (StackOverflow)

How to kill tasks in Windows 7 when even Task Manager won't open or respond?

Occasionally one of my computers will get so bogged down that everything locks up, Ctrl+Alt+Del doesn't work, Task Manager won't open, or they work, but are opening so slowly that it will take hours or days to shut down other processes and regain control of the computer, etc.

Is there a way to, for instance, force Task Manager to be highest priority so it always opens immediately with Ctrl+Shift+Esc even when some other process/driver is hogging the CPU? Is there some other program that can run in the background and open immediately like this?

This question isn't about fixing "underlying problems". No matter how much memory you have, it's still possible for a rogue process to eat it all up and lock up the computer in page fault thrashing, hog the CPU, etc. This question is about how to take back control of the computer when that happens.

Basically when these kind of lock-ups happen, I want to open some kind of task manager that pauses every other process and allows me to kill one of them, and then let everything resume so I can save my work, etc. Otherwise my only option is to hold down the power button.

Antifreeze is supposed to do exactly what i want, pausing all other applications and starting a task manager to kill the offender, but in my testing, it actually does neither.

Source: (StackOverflow)

How do I quickly stop a process that is causing thrashing (due to excess memory allocation)?

We've all experienced it--some program is asked to do something that requires a huge amount of memory. It dutifully tries to allocate all this memory, and the system immediately begins thrashing, swapping endlessly and becoming sluggish or non-responsive.

I most recently experienced this on my Ubuntu laptop due to a Matlab script trying to allocate a ridiculously huge matrix. After ~5+ minutes of thrashing, I was able to Ctrl-F1 to a console and kill Matlab. I would much rather have some hot-key that would have given me control of the system immediately and allowed me to kill the offending process; or, perhaps, simply silently refuse to allocate such a large buffer.

  1. What is the quickest way to regain control of a Linux system that has become nonresponsive or extremely sluggish due to excessive swapping?

  2. Is there an effective way to prevent such swapping from occurring in the first place, for instance by limiting the amount of memory a process is allowed to try to allocate?

Source: (StackOverflow)

Interrupting the "Spinning Wheel of Death"?

I am running Snow Leopard. It is up to date. Every few days, I get the "Spinning Wheel of Death."

  • I can't do anything except hold down the power button to shut off my MacBook Pro.
  • I've even tried a kill -9 -1 from a root shell that was already opened. It just hangs.
  • The Spin Control app just says "Sampling" on a few of the apps but is unresponsive.

Do I have any other options to shut down my laptop? I don't like to just power it off.

Update: I have no idea which app is doing this. At the moment it appears random. My fan does not spin up. Maybe it's a networking thing?

Update: Dead again. This time I had X11 running and no matter what app I switched to, I got that app's menu bar and the X11 screen. I ping and the Internet doesn't respond. My Apple router is working because I'm streaming Pandora over WiFi. I turn off the wifi and I'm still screwed. I try to power off and it won't shutdowm because X11 is running. If course, I can't kill it. Press and hold... boom. This is not how an OS is supposed to work!

Source: (StackOverflow)

Windows 7 running slowly with low CPU usage and memory

I have a relatively new (under 2 yrs old) Windows 7 machine. It has 9GB of RAM, and an i7 core CPU (930 @ 2.8GHz w/ 8 CPUs). After about 8 months since a clean install, I noticed my computer was running slowly. I figure it was fragmentation etc, and I did a complete wipe & clean reinstall.

However, my problems are somehow persisting. The computer is running painfully slowly (but in leaps and bounds - sometimes it will work fine for 3 hrs, then suddenly freeze up just from clicking the start button). The 'freezes' happen randomly - not during any especially intensive computing. I initially thought something might be eating through my CPU and/or Memory, but Task Manager indicates that neither the CPU or Memory spike. In fact, even during serious lag, CPU usage remains at less than 5% and Memory at ~ 1.5GB.

It's beyond me why a fresh install on a powerful machine is performing so poorly. And it certainly is frustrating! What could be causing the poor performance, and what can I do to fix it?

Source: (StackOverflow)

increase desktop responsiveness on linux while swapping

All GNU/Linux distributions I tested so far have the problem that whenever the ram gets filled and the system begins swapping, the whole desktop and graphical user interface becomes unresponsive as hell to an extent that sometimes I have to wait about 5-10 seconds after having moved the physical mouse until the mouse pointer is actually moving.

This is kind of an annoying behaviour, especially on systems with low ram.

Is there any way to give some applications/jobs, like the desktop environment etc., a higher priority to stay in ram than other applications, so that the application actually hogging all the memory gets swapped before the desktop environment etc.?

EDIT: I'm talking of the case when the entire RAM is used so it will always start swapping if it isn't disabled (I don't want processes to be killed randomly). I had this problem not only in low ram environments, but as well with 8GiB of ram on my desktop machine, partly due to many VMs partly because of memory leakage. ZRAM isn't a solution either as it's only delaying the problem. The only solution I can think of for this problem is some userspace utility or kernel API that allows to prevent certain jobs to be swapped at all or at least make it very unlikely. Does anybody know another solution or knows anything about such a tool or API in existence or being planned?

2nd EDIT: ulatencyd doesn't seem to work with newer versions of systemd, according to and . This may be because systemd took over full control of cgroups from a userspace perspective if I understand it correctly.

Source: (StackOverflow)

Why would Thunderbird regularly hang for 10 seconds

I've been using the Thunderbird e-mail client for years on three different operating systems: XP, Vista, Windows 7.

On all of these operating systems, it has always had the problem of e.g. I'll be writing an e-mail and suddenly it will just freeze, I can't type, and 10 or 20 seconds later it will "come back" and I can type again. When I look at the task manager when it does this, the CPU spikes to 100% during these times and the guilty process is Thunderbird.

The problem is not always the same:

  • on XP it started out fine and these black outs got longer and more frequent
  • on my Vista installation it would happen only once every 20 mails
  • now on a new installation of Windows 7, it happens almost every e-mail I type and often when I pull the scrollbar down it will freeze, "(Not Resonding)" will come up in the title bar, and I have to wait 20 seconds before I can use it again.

What could be causing this? Has anyone else had this problem with Thunderbird?

Source: (StackOverflow)

Computer randomly freezes when playing games

My computer just randomly freezes when playing certain games. It has happened to me in Battlefield: Bad Company 2, Call of Duty 4, and Blacklight: Retribution. It has not happened to me with other games like Tribes: Ascend yet, which leads me to believe it is a software-side issue related to maybe DirectX or PhysX?

Also, temperatures seem stable. I used RivaTuner combined with MSI Afterburner, and at the time of freezing with BF: BC2, it gives: 62C, 67% GPU usage and 78. 8FPS. During the session the max I have seen was 65C and 97% GPU usage.

On Blacklight: Retribution, I've heard other people complain about the problem too. This is why it is such a mystery to me, is this actually a driver problem, or more a game problem? I've been able to play these games for long until I re-installed Windows 7 (because it was growing too full and slow). Before I had a 32bit Ultimate version, and now 64bit.


O/S: Windows 7 64bit Ultimate
CPU: Intel i5-750 @ Default 2.66 GHz
PSU: CoolerMaster Real Power M520 (520W)
MB: Gigabyte P55M-UD2
Catalyst Control Center version (in "About"): 2012.0214.2218.39913

Source: (StackOverflow)

Unfreeze a frozen osx UI using ssh without shutting down all applications?

My mac freezes occasionally, and most often I simply restart it by holding down the power button for 5+ seconds.

Today however, I had been running a huge file scan for 14 hours when the UI froze completely, and I’d rather not wait another 14 hours!

Symptoms of the frozen UI: Nothing happens when using the keyboard (except for the caps lock light turning on/off). Naturally, force quit does not come up. Moving the mouse moves the cursor on the screen but clicking does nothing.

Using another Mac on the network, I can access the mac by SSH. I saw that the RAM was almost full, but CPU activity was modest. Things I tried to unfreeze the mac:

  1. Shut down / kill Chrome, iMovie, Photoshop and other applications that I didn't care about shutting down. Did help the RAM usage down, but did not help in unfreezing the mac.

  2. Shut down the Finder and Dock processes. No help.

  3. Activated Screen Sharing from the command line and tried connecting remotely. The password dialog comes up (indicating that screen sharing indeed is activated) but after supplying password, the progress indicator just spins for eternity and nothing happens.

  4. Tried suspending the user session from the command line:

/System/Library/CoreServices/Menu\ Extras/ -suspend

This command just hangs in the SSH session and nothing happens. Needs to be aborted using ctrl+c. Using sudo makes the command return immediately without any effect.

Not even killing WindowServer (sudo killall -HUP WindowServer) helped, and running a graceful restart (sudo shutdown -r now) only made the computer freeze completely (no more cursor movements nor ssh access). Only the power button force shut-off worked.

Had to wait another 14 hours for the file scan to run again. Is there any other way to unfreeze a mac in this state? Would be good to know for future reference…

Source: (StackOverflow)

How to diagnose computer lockups and freezes?

I built a desktop computer a couple years back with the following specs:

  • CPU: Intel Core 2 Quad Q9300 Yorkfield 2.5GHz 6 MB L2 Cache LGA 775 95W Quad-Core Processor BX80580Q9300
  • Motherboard: EVGA 122-CK-NF68-T1 LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard
  • Video Card: Two EVGA 256-P2-N758-TR GeForce 8600GT SCC 256 MB 128-bit GDDR3 PCI Express x16 SLI Supported Video Card
  • PSU: SeaSonic S12 Energy Plus SS-550HT 550W ATX12V V2.3 / EPS12V V2.91 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC Power Supply
  • Memory: Two G.SKILL 4 GB (2 x 2 GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-4GBPQ

Since its inception, the machine has periodically locked up, the regularity having varied over the years from once a day to once a month. Typically, lockups happen once every few days.

By "lockup" I mean my computer just freezes. The screen locks up, I can't move the mouse. Hitting keys on my keyboard that normally turn LEDs on or off on the keyboard (such as Caps Lock) no longer turn the LEDs on or off. If there was music playing at the time of the lockup, noise keeps coming out of the speakers, but it's just the current frequency/note that plays indefinitely. There is no BSOD.

When such a lockup occurs I have to do a hard reboot by either turning off the computer or hitting the reset button.

I have the most recent version of the NVIDIA hardware drivers, and update them semi-regularly, but that hasn't seemed to help. I am currently using Windows 7 x64, but was previously using Windows Server 2003 x64 and having the same lockup issues.

My guess is that it's somehow video driver or motherboard related, but I don't know how to go about diagnosing this problem to narrow down which of the two is the culprit.

Additional information re: cooling Regarding cooling... I've not installed any after-market cooling systems aside from two regular fans I scavenged from an older computer. The fan atop the CPU is the one that shipped with it. One of the two scavenged fans I added it located at the bottom tower of the corner, in an attempt to create some airflow from front to back. The second fan is pointed directly at the two video cards.

SpeedFan installation and readings Per studiohack's suggestion, I installed SpeedFan, which provided the following temperature readings:

  • GPU: 63C
  • GPU: 65C
  • System: 76C
  • CPU: 64C
  • AUX: 36C
  • Core 0: 78C
  • Core 1: 76C
  • Core 2: 79C
  • Core 3: 79C

Update #3: Another Lockup :-( Well, I had another lockup last night. :-( SpeedFan reported the CPU temp at 38 C when it happened, and there was no spike in temperature leading up to the freeze.

One thing I notice is that the freeze seems more likely to happen if I am watching a video. In fact, of the last 5 freezes over the past month, 4 of them have been while watching a video on Flickr. Not necessarily the same video, but a video nevertheless. I don't know if this is just coincidence or if it means anything. (As an aside, each night before bedtime my 2 year old daughter sits on my lap and watches some home videos on Flickr and, in the last month, has learned the phrase, "Uh oh, computer broke.")

Update #4: MemTest86 and 3DMark06 Test Results:

Per suggestions in the comments, I ran the MemTest86 overnight and it cycled through the 8 GB of memory 5 times without error. I also ran the 3DMark06 test without a problem (see my scores at

So... what now? :-)

Any further suggestions on what to check? Is there some way to get a stack trace or something when the computer locks like that?


I have never did figure out the particular problems, but based on the suggestions here and elsewhere, I'm presuming it was a motherboard issue. In any event, I recently upgraded my system, buying a new motherbeard, PSU, CPU, and RAM, and that new rig has been working splendidly the past several weeks. I am using the same graphic cards as in the old setup, so I think it's safe to reason that they weren't the cause of the problem.

Source: (StackOverflow)

Windows 7 is stuck at "Starting Windows" when I attempt to boot computer

Basically, whenever I turn on my computer, it gets to the Starting Windows phase and just stays there. The startup animation still plays, yet it gets nowhere.

  • I have tried booting into safe mode, however it gets stuck at loading CLASSPNP.SYS. It then freezes there and doesn't continue booting.

  • I have tried booting into recovery mode from the hard drive, and it freezes after displaying the background image. I have tried booting from a recovery CD, which works, and I was able to use system restore. However, using system restore did not fix it, and it still is stuck at the Starting Windows screen.

  • I have tried booting a Windows CD (Windows 8 Retail Installer) to see if I could upgrade it to fix this issue, however that froze at a blank screen after it got past the boot logo.

  • I have tried changing around the BIOS settings (including resetting), to no avail.

  • I have tried re-plugging the internal PSU cables (this is a custom-built desktop), yet this has changed nothing.

  • I can boot into a loopback Ubuntu install on the same drive, which works fine, other than the fact that it has issues with some of the USB ports and the network card.

  • This system has worked fine for the past few months, completely stable, and nothing in the configuration has changed before this error started happening.

  • Startup Repair on the Windows recovery CD doesn't find any issues.

  • Unplugging my secondary hard drive or swapping around memory doesn't change anything.

  • The hard drive itself is fine, it hasn't shown any signs of failure and once again, boots my other OS fine.

If anyone could help with this, that would be great. I can't seem to find any possible solution to this.

If it makes any difference, my system specs are as follows:

  • AMD FX-8320
  • Gigabyte GA-970A-D3
  • 4GB of DDR3
  • Radeon HD 6870
  • 550w PSU

I'd like to not have to reinstall Windows, for I have more than a terabyte of data that I would have to back up if that becomes the only option.

EDIT: I have since tried the following:

  • Tried the solution involving restoring files from RegBackup, which changed nothing.

  • Tried testing everything with Hiren's boot CD, everything comes back as fine.

  • Tried disabling everything unnecessary in the BIOS and unplugging everything unneeded, it still hangs.

  • Tried swapping out every possible combination of RAM, it still has the same result. The RAM is not at fault it seems

  • Tried every GPU I own (which is many!) and it still hangs at the exact same place.

  • Tried minimizing the power consumption as much as possible, even using an old PCI graphics card. It still hangs at the same place in the same way, signifying that it's not the PSU at fault.

  • Tried resetting the BIOS again, still nothing.

  • Tried every possible combination of BIOS options, even downclocking everything, it still hangs in the same spot.

  • Tried upgrading the BIOS from version FB to FD, which changed nothing.

Based on this, I would conclude the motherboard to be at fault. Are there any other possibilities? I don't want to spend $150 for a new motherboard.

EDIT 2: This is what it gets stuck at when I try to boot into safe mode:

enter image description here

Note the slight graphical corruption at the top of the screen. No matter how I set up the system, this seems to be there. In addition, either it has stopped booting into safe mode now, or it takes upwards of 2+ hours, and I haven't left it running for that long.

Source: (StackOverflow)