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Why does my computer randomly reboot without warning?

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Summary: Random reboots are annoying because you can easily lose what you're working on at the time. Random reboots are difficult to diagnose, because there are many possible causes.

My computer likes to turn itself off and restart itself of its own free will. I do have virus and spyware protection. It doesn't present any error message, it just shuts itself off and reboots no matter what I am doing on it.

I hate it when that happens. It's one of the most annoying things a computer user can face. You're working along and all of a sudden *poof* - everything's gone. Be it a random reboot, or the infamous "blue screen of death", it's very, very frustrating.

The problem is that this can be caused by so many things, it's difficult to nail it down quickly.

Let's run through some of the possibilities, and what I'd do.

Malware

You've touched on one thing I always look at first: viruses and spyware. Do make sure that your scanners are running, and are being regularly updated with the latest databases of spyware and virus definitions. For anti-spyware tools, that should happen daily - anti-spyware tools typically do so less often.

Software

If you're running Windows 9x (meaning Windows 95, 98 or Me), there's about a 50/50 chance that the problem is a software problem. Because of how their design evolved, those versions of Windows were all somewhat more vulnerable to crashing bugs in the software. A poorly written device driver, or even an application bug, could in the worst case scenario cause a system reboot or blue screen.

If you're running Windows XP (or Windows NT, 2000 or 2003), the system is designed more robustly - meaning that it's more difficult for these types of problems to result in a random reboot or crash. Not impossible, just much less likely.

If you've made a recent change to your system, perhaps installed a new software package, or a new piece of hardware, and these problems started happening thereafter, that's a likely clue. Depending on the software or hardware, my first reaction would be to look to the vendor for reported problems and possible updates. In particular, device drivers are the most likely to cause crashes and reboots without warning.

As I said, software related reboots and blue screens have become more rare under Windows XP. However you should still make sure that your system is as up-to-date as possible, particularly including drivers for recently installed hardware.

I know that many folks have become suspicious of Windows Automatic Update for various reasons, but I've not heard of any crashes resulting its use. I still recommend it as the best way to keep Windows up to date.

Hardware

I will say that if your computer is still under warranty, you need to talk to the manufacturer first. You should exhaust all your options in getting them to repair a failing machine before you head out on your own and possibly void your warranty.

Naturally, if you've recently installed new hardware, that's a possible clue. You might consider removing it temporarily to see if the problem abates. If it does, it points to either the device itself being the cause, or perhaps the system power supply, as I'll discuss in just a minute.

If your computer has been running fine for some time, and you haven't installed any new hardware or software recently, then my tendency would be to start suspecting various hardware components.

Perhaps the most common are failing fans. The fans that move air through your machine to keep it cool are critical to its operation, and are often the first to fail - either due to accumulated dust and dirt, or simple age. When the fan stops working, the machine overheats, and when the machine overheats - it crashes. Randomly.

Next most common is a failing power supply. Power supplies can fail slowly - meaning that they can become 'marginal' before they fail completely. And the symptoms of a marginal power supply are - you guessed it - random crashes. This is one of those cases where replacing the power supply (or having someone replace it for you) is often an inexpensive test. Particularly if you've added more hardware to your system over time, you may simply be demanding more of the power supply than it was designed to provide, so an upgrade might well be in order as well.

"... Which leads to the ultimate predicament... it could be anything. Quite literally.

I have this gut feeling that memory is failing just a little more frequently than in the past. I won't speculate as to why, or even if my observation is accurate. The good news is that there are tools specifically designed for testing memory. Memtest86 is one such tool that performs an exhaustive test of your computer's memory. Microsoft also provides a Windows memory Diagnostic. Both tools run from a bootable floppy or CD (Windows cannot be running for the tests to exercise all memory), and both tools are free.

Naturally, it's also possible that the fault lies elsewhere. You motherboard, an add-in card, even your disk drives or video card. Which leads to the ultimate predicament... it could be anything. Quite literally.

One of the more common repair techniques is to make an educated guess at what might be wrong, replace that component, and keep repeating until all the components of your computer have been replaced, or the problem goes away.

Unfortunately, doing that is beyond the resources or desire of most computer owners.

My approach

So here's what I would do, when faced with a randomly rebooting computer:

  • Yes, I would consider upgrading to Windows XP, if the machine was capable of it.

  • Make sure that anti-virus and anti-spyware utilities are running and up-to-date.

  • Make sure that the operating system and all device drivers are as up-to-date as possible.

  • Run a memory diagnostic such as Memtest86 or Windows memory Diagnostic.

  • Run a hard disk diagnostic such as SpinRite.

  • Run a motherboard temperature monitoring tool such as Motherboard Monitor - it's a free tool that will report your CPU's temperature among other things, and will let you see if the machine is overheating for some reason.

At this point I've done pretty much everything I can that doesn't involve opening the computer. If the problem isn't evident or resolved, we need to get a little more serious. This might also be the time for some to simply take their computer in to a technician for diagnosis.

Next, I'd open up the computer and:

  • Carefully vacuum all the dust out of the machine.

  • Make sure that the fans which are accessible are running properly. If not, I replace them. If the machine doesn't crash as quickly with the cover off, that's often a sign of overheating.

  • Remove as many optional hardware components as possible that would still allow the machine to run. If the problem disappeared, I would re-install components until it reappeared, and then remove other components to make sure that the problem was associated with only a specific component.

  • Re-seat all remaining and accessible connectors and expansion cards - sometimes problems are as simple as a loose connection.

At this point we've done pretty much everything we can with what we have on hand. Next up, we start spending money (or, perhaps if you're a geek, pulling from your spare parts bin), and go down the "replace parts until it works" path. This is another jump off point for many - it's definitely easier to simply take the computer in to a technician for diagnosis.

  • I'd replace the power supply first. Unless there's other data that says the problem is likely to be elsewhere, I'm just playing the odds here. If I went this far, and I planned to keep the computer for some time, I'd also consider upgrading to a higher wattage supply at the same time. Replacing a power supply is only moderately difficult.

  • Next up, would be the motherboard. This is a bit of work, as it often involves tearing the entire computer apart.

  • Lastly, I'd consider replacing the computer.

In reality, unless you're really interested in playing with the hardware and trying the "replace it 'til it works" approach, I'd recommend skipping this last set of items completely and taking it into a repair shop to let them figure it out.

And, naturally, before you do so, it might also be time for a cost/benefit analysis: will it be cheaper or more effective to simply replace the computer than to fix it? I'm not at all saying that it will be - it depends on the availability and going rates for computer repair in your area, and the potential cost of fixing whatever is broken. But this is the time to at least do the math and compare.

Related:

Article 10570 | Posted August 1, 2006

Recent Comments
38 Comments

Ok i got my new Pc i was very happy about it. GREAT pc. But now when ever i turn my power button on the Screen dosnt turn on. :( totally black nothing there. so after i waited for like 5 minutes i push the restart button then the screen comes back up WOOT ^^.. then after it loads suddenly it restarts randomly :( sometimes it loads and i start playing a game then restarts again.( GETS SOOOOOO ANYOING!!!!!! >:(..) after that everything works sometimes then it Froze the Pc WTF????? would u know any of these problems????
this gets so fustrating if u could tell me what the problem is that would be EXCELLENT!!! Thanks

Posted by: Juni at January 20, 2008 7:59 PM

sir,
please let me know what will be the reason if the laptop gets off all of a sudden while working on it in every 6 to 8 hours. then i have start it again it make me worry.i will thankfull if u can suggest me in simple way so that i can repair it by myself.

Thanking u .

yaqub

Posted by: yaqub at April 30, 2008 11:01 AM

ererytime i log in on facebook my computer restart...what would do that

Posted by: daniel at May 1, 2008 10:53 AM

my computer will not boot to desktop and it will always restarting

Posted by: frank at May 7, 2008 2:27 AM

My windows xp pro sp2 computer has started random reboots (often) it reboots long before I have time to run a virus and spyware scanner.

It doesn't do that at all when I'm in safe mode - doesnt that mean it can't be a hardware issue?

I'm currently scanning while in safe mode. IN regular mode - I have the windows firewall on.

Thanks

Posted by: John Hansen at May 8, 2008 8:28 AM

My laptop restarts itself often times when I have closed it. This is pretty much the only thing I do if I am done with it for the day or am getting ready to leave a place. When I close it it goes to sleep and when I open it back up again I sometimes get the bsod or when I wake up in the morning and open it I will find that it has restarted itself. The computer is a toshiba intel running with windows vista.

Posted by: Ashley at May 28, 2008 5:10 AM

After trying all of the above, I realized IT WAS THE POWER/RESTART BUTTON WHICH WAS BAD!!! SIMPLY DISCONNECT FROM THE MOTHERBOARD TO TEST IT.

Posted by: Steve at June 20, 2008 3:26 PM

hi,
i have been having the same problem with my comp.....just reboots for nothing...this has to be the most annoying thing i have come across.
when i looked at event viewer it was saying that it was a uph cleaner and it was making a profile dump. then i looked at my programs and there was a program called user profile clean up......i think it was part of a microsoft update. anyway i uninstalled it 2 days ago and i have had no problems with computer since ( fingers crossed ).

was this a good thing to do ( the uninstallation ) ? and will it hamper my computers performance?

thx and peace :-)

Posted by: layton at July 23, 2008 4:49 AM

Hi, i Have windows XP Media and it keeps rebooting when i turn it on. I get the option of Save mode and all the others but when i choose one it just reboots again to the start. Please help.

Posted by: Jonaythan at October 8, 2008 9:32 AM

I HAVE A PROBLEM MY PC DIDN'T BOOT UP SOME TIMES AND THE SCREEN STILL BLACK AND I MUST PUSH THE RESTART BUTOON TO OPEN IT

Posted by: kajol at October 26, 2008 2:21 AM

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