green screen on videos?

i got my pc a video card installed about 6 months ago (nvidia geforce fx 5200, 256 mb), it all worked just fine but all of a sudden it started to turn videos viewing into laggy green screens. it only happened sometimes tho, mostly after having the pc on for a while. sometimes opening video editing programs like adobe after effects would make my pc shutdown by itself or even freeze. downloaded their sp2 patch from the nvidia website, but it made it worst, now quicktime formart videos and dvd's both automatically get that green screen, and their websites provides no info on this. anyone else had this problem?

update driver, check cooling in the driver's temperature dialog. check that it's not an os/directx problem...

oh yeah, how about checking the hardware acceleration for your card, sometimes windows likes to randomly bump it down, causing all sorts of mayhem.