Help Please- Computer keep restarting whenever try to paly video file

[DC52E55]

My computer keep restarting whenever i try to play any video files at all (DVD,VCD, video files from harddrive, etc). I am a noobie and dont know how to fix the problem.

I have 3200+ XP 64 and ASUS A8n-E mobo and ATI 800XL video card and i run window X64.

Any help would be really appreciated!