I have been using my EVGA 9800GX2 for 2 days now and it plays games perfectly for hours at a time. But when I play an xvid video, I get this major pixelating green vertical lines that appear after 3-4 minutes of the video running. Then the computer locks up hard and I'm forced to do a manual restart.

Any ideas of what this might be? I know the cooling is fine since I can play COD4 for hours and have no issues.