I've never seen this problem, only a few scattered people have reported it, and I don't have a way to duplicate it. Most likely this sort of thing is below the level of the application, either in DirectX, possibly (but unlikely, or more people would be seeing it) SlimDX, or else in the drivers/OS. There's really nothing that I can do about this until I have some sort of way to duplicate it, and even then it might be out of my hands, unfortunately.