MEDIA crapping out

My computer has been shutting down out whenever i play any sort of media (avi files, streaming media like google video/youtube, even swf flash files). mp3s/music are fine though. i've asked around and someone told me it might be a codec problem. as far as i know, i'm not missing any specific codec because i can always see/hear any video... but does that sound like the case?

- upgrade video drivers
- check for overheating

do like >>2 says

or check your video card compability with your motherboard, because last time i had similiar problem, i'm using gigabyte and geforce and its always crash whenever i played 3d games