Browse this part of the forum (or perhaps the "solved" sub-section). There's tons of threads regarding this issue, and most of them explain how to correct it.
Basically speaking, it's an issue with the GPU. So, start by updating its drivers, and if it's not enough, keep icode]shift[/icode] pressed when starting the game, to access to the "renderer setting" page, and choose a different renderer (generally "angle" should works).