Artifacting and bad drivers?

Hey guys,
A bit confused on this one.

http://img200.imagevenue.com/loc337/..._122_337lo.jpg

There are "gaps" in the circled part of the roof. Now this happens only on certain parts of maps but it never used to do it (in lower resolutions its even worse, the gaps are a lot bigger). The only thing I can think of is that the updated versions of the drivers are doing it. If so, however, WHY?!
I doubt its a heat issue as I booted up my pc and went straight into the game to check it out and its there. (room temp was about 19 deg)

Also
http://img184.imagevenue.com/loc207/..._122_207lo.jpg

This happens in cs when I alt + tab - as soon as I let go of alt+tab it goes away. Everything else is fine. It doesn't happen in any other game, although you can never see the alt tab menu as it just cuts straight to desktop.

So, any ideas guys? :(

Thanks


EDIT: I just did some testing and when you alt tab out of UT3 the screen "parses" to what you see in the 2nd ss and then alt tabs.(only for a split second though)