Strange disply/ graphics card problem

I don't really know how to explain this but very rarely when I watch video my computer can crash or just goes really strange........

It's like the video has become corrupted, kind of like green and red fine lines that come horizontally and vertically across the screen, if I close the video before my computer crashes my mouse has become corrupted like it's been split up in to four icons. This happens very very seldomly it's happened three times in the last 3 months. When I restart everything is fine this bug cannot be replicated.......

Any ideas?

It has happened with different players and when watch online streams. I've go no problems with any games.


Q9650
GTX 8800 Sli
4 Gb ram
Dell 24" monitor.

Check for heat problems.