flickering screen playing mp4 videos

I am using media center 11 on a vista 64 system. When I play mp4 videos, strange things happen. When it is in full screen mode and the controls (volume, stop, start buttons) are displayed, everything works fine. When the controls hide, it looks like the video frame playing at that moment is captured. From that point on, the video alternates between correct video and the captured frame. It appeares like a flickering or flashing. If I move the mouse and the controls appear, the video goes back to normal. The sound is always correct.