I've been working with this computer for about two months due to a sudden shutdown issue. It has been cleaned (of dust and malicious software). I've tested the PSU and run several scans (Norton, AVG, Spybot SD, Malwarebytes, CC Cleaner, Regcure, Advanced System Care 3, and a few others that I can't recall.) It is a custom tower w/ a Foxconn MOBO and an AMD Athlon 64 X2 in an AM2 socket w/ 3 GB of 5200 DDR2 memory, and a WD 320 Gig HDD. The owner is beginning to think I'm a joke. I can't fix his desktop.
I'll keep my day job for now.
Any clues would be appreciated.

Markosan again...
I forgot to ad this machine is running XP Home.
Is there anybody out there?

Thanks, Mark