Random freezes, at wits end

[garygary]

Okay, this is a problem that has been annoying me for some time, and I don't know what else to do.

At seemingly random intervals (although the chance of freezing seems to increase while playing a game, can't say for sure though), my computer will completely freeze. The sound will loop, mouse will stop moving, not even the caps lock light will come on when I press caps. The only way to fix it is to manually reboot the computer. My computer will also occasionly freeze while windows is loading as well.

I am running Windows Vista Home Premium, with an intel E6600 core 2 duo processor, Asus M2N32e SLI motherboard, 3 Gigs of RAM by Gskill and a GeForce7950GT graphics card from Leadtek. This problem has only started recently, although it was not after installing anything or changing any settings.

The computer is on a home network with several others, one of which has contracted a similar problem at about the same time. However, this computer will only freeze when something is accessed, and can sit on the desktop after logging in without freezing. Mine has frozen while starting windows, as well as just after logging in before I accessed any files or started any programs. This had lead me to believe that it is a virus, so I reformatted my computer and still have the problem. I did back up some files before formatting however, and have accessed them since.

I am not sure if this is a hardware or software issue. Personally I think it is more likely to be a particularly vicious virus, that is on my home network or in my files and as such can reinfect my computer. Running AVG, Spybot, Spycatcher and windows defender scans however have found nothing. If it is a hardware issue, why does it occur so erratically?

Any help or advice on this would be much appreciated, even if they can just point to somewhere that I can find more information.

[-pops-]

Is there any clue in the Event Viewer when this happens?