Need help

I have undetermined problem which makes me insane. My computer crashes during ALL games, including old 2d stuff. Sometimes even in some applications. Applications ranging from Itunes replacements like ephpod to rocket dock. This is NOT a software issue. The problem persisted even after full format and on freshly installed Windows. RAM modules are OK. HD is clean. No infections. CPU temp is normal.

The graphic card is NOT the problem; I tried several and the problem remained.
Here is the list on my hardware.

mobo: ASRock P4VT++
PSU: Codegen 300W (the problem remained even with an old Radeon 9000 with 64mb; don't think it's dying.)
CPU: Intel Celeron 2,4 Ghz
CPU fan: Zalman
RAM: 768mb, all modules are the same brand name/speed
HD: Hitachi Deskstar 80Gb
Card: ATI Radeon 9600 XT with the latest Omega drivers
OS: Win XP SP2

All drivers are installed; NOD32 is defending the machine.

Please help. I don't know what to do. Thank you for your time.

>>4
You know, I think you're onto something here.  I missed a step.

1. Try the BIOS first, in case it has diags built in.

2. If not, try http://www.asrock.com/ to look for any diags.  Run them.

3. In either case, when you find a faulty area and you determine that you can live without it, either disable the component in the BIOS or do it in XP.

Let us know what happens.