System restart randomly AMD

Usually MY computer Runs fine But sometimes when playing

videos my computer randomly restarts. Through Research I

was advised it was more than likely a software issue. I run

Win XP and usually run a registry fixer and the problem

will disappear for a few days and then return. It is really

random I'm not stressing the CPU or anything really. I'm

just watching Videos on Hulu. I also Notice that sometimes

the computer restarts if I leave it on for a while. At

first I though it was because it was getting hot but it's

not, heat is not the problem since CoreTemp showed max temp

of 54C.

Prime95 fails shortly after starting with the message

"FATAL ERROR: Rounding was 0.5, expected less than 0.4

Hardware failure detected, consult stress.txt file. "

Specs:

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AMD Phenom 9600 Agena 2.3GHz 4 x 512KB L2 Cache 2MB L3

Cache Socket AM2+ 95W

ECS BLACK SERIES A780GM-A AM2+/AM2 AMD 780G HDMI ATX AMD

Motherboard - Retail

OCZ 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500)

Dual Channel

SAMSUNG Spinpoint F1 HD103UJ 1TB 7200 RPM SATA 3.0Gb/s 3.5"

Internal Hard Drive - OEM

1 LG DVD Rom

Coolmax / V-400 / 400-Watt


All video and audio onboard