Hey guys, I've got a really big problem. I have a Geforce 5600 FX 128MB AGP video card. For some reason whenever I do anything moderately graphical, my screen goes haywire after about 5-10 minutes. I see fuzzy curved distorted zig zags on the sides of my screen, and 5 mins later it starts to go blank. This happens even when not in fullscreen.

Compiz seems to run fine, but when playing with CUBE2, Hedgewars, Nexuiz, or even the cooliris firefox plugin, it just goes crazy. I didn't have this problem before, so I think it must have been something I messed around with.

I think it may be an openGL issue, refresh rate problem, or maybe even an overheating issue.
pleeeeeeeeease help!!!