Shutdown with no warning...virus has been detected

[SpiderElls82]

Greetings all,
I ran into a troubling problem with a client of mine. He's an end user...no network. There are a few backdoor viruses on there that AVG evidently cannot remove. I'll run recovery console and play with the registry later to take care of that. However, my question is...would this problem most likely be...
a.) The backdoor viruses on there
b.) A hardware driver issue
c.) something else?

If you need more information or have any possible solutions. Please get back to me. I'll be checking this tomorrow. Thank you for your time.
Ben ->
__________________
XP Pro Upgraded from ME.
1.1 GHZ CPU
256 MB RAM
DVD Drive
CD Drive
Zone Alarm Firewall
AVG Anti-Virus
All-in-One Secretmaker
Spybot S&D
Ad-aware 6.0

 

[bcastner]

Check the event logs, but usually they will be empty with a sudden shutdown.

My guess would be a heat related failure of RAM or possibly the CPU.
Check the RAM:

http://www.memtest86.com/#download0

http://oca.microsoft.com/en/windiag.asp

You might consider installing "Motherboard Monitor" to track heat levels:

http://mbm.livewiredev.com/download.html