random shutdown

I am having a major problem with my son's computer going into a random shutdown mode. I have checked for viruses, even took it to best buy and had them run a diagnostic test on it and they found no problems with the computer at all. The only thing they did find were 3 small bios viruses which were removed. Additionally I might add that the computer did not shut off once while under diagnostics, they did say these are bios run testing and not done through windows. Prior to taking it to best buy I even did a full reinstall of windows. I thought perhaps it was the actual outlet, so I connected it to a different outlet. My son was able to turn it on yesterday after bringing it home from best buy and totally reinstall all the discs and upgrades for WOW and play for several hours. I also need to add that since we bought the computers he has been playing WOW and had not had any problems before this. This morning he went back to the computer and it was off, once again, and now it is back to shutting down randomly. Please any suggestions would be greatly appreciated. This computer is a little over a year old, so age can not be a contributing factor.

 

"3 small bios viruses", interesting.

Can you navigate to C:\Windows\Minidump please, if there are any *.dmp files there, could you upload say, the last 3? Copy them to the Windows Desktop first, then right-click them and select Send to > Compressed folder, that should create a zip file with the dmp name, upload and attach the zip please.

 

I'm not familiar with this :confused

however, if they did find anything, I would suggest trying to run the malware removal steps here:
http://forums.majorgeeks.com/showthread.php?t=35407

now, if you cant get to these because of the shutdowns. then you will have to address that first. Most shut downs occur because there is a driver conflict, or hardware issue. Also, it could be an overheating issue. Shut the computer down and unplug it. try to get all the dustbunnies out of the fans and grills.
To narrow down further, disable automatic restart after an error occurs. You didnt specify which operating system this is. they are very similar anyway:

When/If your computer gets an error, it should display a blue screen that give some information about the error. use this information and search microsoft.com for possible fixes.