Well, I had it happen to me on SHarqi too. I think it happens if you have some of your graphics settings up too high. For me it was dynamic lighting/shadows, so try turning those down and see if it works. If lowering the settings doesn't work, then I'm not sure.
Uh ohs. This looks VERY familiar (same spot and everything). I had to get a new video card in the end. Turns out it was a heat issue or a dud card. Drivers fixed it momentarily.
My state was founded by Batman. Your opinion is invalid.