[Lasmori]

This generally happens (to me at least) when running in windowed mode and the window gets resized slightly from the resolution it's trying to run at.

If you are using WinEQ, it may help to tell it to reset the window. I've noticed that this can still happen on live while using Inner Space to simulate "windowed full screen". I can't recall exactly how I generally go about fixing it as I've not had to deal with the problem for half a year or so now.