It's a driver-related bit, on new ATi drivers, like someone mentioned above. I had it for a while, but was able to "fix" it by going from the latest ATi Catalyst drivers to the recommended drivers for my card (some makers, VisionTek for example, will offer older or slightly tweaked drivers for some cards). I think the Omega drivers may not have the problem either, I don't remember seeing it on them. No amount of playing with desktop composition is likely to fix it, though (or didn't for me). Installing outside of Program Files helps a lot, but not for this particular bug.
Usually, though, if you get this, the game itself will be just a black screen. Does that happen too?