Computer keeps crashing under windows.

[AsmoFireEye]

I just finished building my first computer, and I've got a problem with it that just won't seem to go away no matter what I do. When running applications (games, internet explorer, even disk defrag or error checking), the computer just sort of freezes up. I don't know how to describe it exactly...the monitor screen either goes blank or becomes extremely distorted and freezes up, the speakers either go dead or emit a looping series of blips and/or high-pitched tones, and nothing short of a manual power-down does anything. System specs:

AMD Athlon XP 3000+ Barton
PowerColor Radeon 9800SE 128MB
Soyo KT600 Dragon Ultra Plat. Mobo
768MB PC3200 RAM (Crucial)
SB Audigy 2 ZS
WD 80GB IDE HDD

Since it's my first time building a comp, I assumed I'd done something wrong while assembling the hardware, so I started swapping out parts. Swapped out the PSU for a new Antec 400W, swapped out the vidcard for a new Radeon 9200. Neither fixed the issue. I ran Prime95 for a full 24 hours and Memtest86 for 10 hours, using all tests. Neither turned up any errors or warnings. I've reseated the RAM and sound card, and reformatted the hard drive, and still nothing. Can anyone shed some light on the situation? Any help would be greatly appreciated.

 

[AsmoFireEye]

One thing I forgot to add, the comp. only freezed up after Windows loads, not during the BIOS checks or after booting from any discs.

 

[Harvey]

Get a copy of DOCMEM, and run thorough test.

You may also want to try some good diagnostic software. I like WinDoctor in Norton System Works, but there are others.

Hope that helps.