I have never heard of this particular problem. I would try shutting down all non essential programs. And then see if the problem repeats itself.

It could be a program like the dock, is messed up. You might try uninstalling and reinstalling. It could be another program that you have recently installed. Try removing any programs you have installed lately. Then see if it fixes it.

It could be a memory problem. IN the task manager, how much memory are you using?

Keep us posted.