I guess you are using an AMD graphics card and you are seeing the result of a known driver bug.
Change driver to current Catalyst 13.2 beta or Catalyst 12.8.
See thread: Black pixels on certain colours
Installed the latest beta driver and it's fixed! Thanks!
At least one of these questions comes in per day. It's hard to imagine AMD has let it go this long.
if nothing else it's a good way to make answer points.
I see that 13.2 has been at beta 7 level for 2 weeks now... Probably means they've submitted it to Microsoft for WHQL certification, so hopefully we'll see a release soon.
It's a strange problem to describe so unfortunately I didn't find that other post about it. Or any of the other posts haha!
And lets hope so - this is quite an obvious issue!