My gfx card seems to hate third-person view games.

Whenever I am playing one, and I'm in a city type environ (walls around me) I have these graphical "spikes" that shoot from my character. Usually it's just annoying, but recently I bought Prince of Persia: Two Thrones and it makes it nearly unplayable...

I tried re-installing the newest Catalyst Driver from ATI but that didn't help.
BTW I have an ASUS ATI 9800xt