Graphical glitches - coloured lines

[podcat]

I get that a bit on a few games. I have a Nvidia 7900gt card. The glitches never used to happen but were introduced with their more recent drivers.

this usually happens due to:
1. overheating. try running with the computer case open, and an open window or something nearby and see if it helps.
2. actual physically damage/manufacturing error on the cards memory.
3. some sort of driver screwup. try going back to older drivers and see how it works, or just reinstalling the ones you have.