I've never really had this problem, and I know I'm not being of much help. I'm not really a techincal fixer sort of guy, I was just trying to clear up your information so that someone else may have a better idea and may have the right solution for your problem. Sorry.
All I can say is, if you're using a laptop then disregard this. Maybe its a monitor/graphics card problem? Compatibility error of sorts with a certain resolution? Try different video card or monitor if accessible, I really dont know haha. (Just blowing stuff out my a** now).
And maybe try a clean re install of WT. (I know its a burden but its worth a shot.
Sorry I couldn't help much. Goodluck.