What OS are you running. If it's Vista or 7, it might have something to do with it, since there was something on the forums about NOT TO INSTALL the game in default c:/program files... something folder, because it would not install properly or something.
Also did you tinker display options via config shield? might have something to do with post processing. I don't know
just throwing ideas
Also did you tinker display options via config shield? might have something to do with post processing. I don't know