Right click My Computer, select properties.
Click Hardware tab. Down by the middle, find Device Manager. Once open, select View, on drop down click show hidden devices.
Do you see any yellow exclamation points? If so, right click and select properties. This will open a troubleshooter for that device.
What type of computer do you have? I think it is probably a video card or display adapter issue. Check manufacturers website(s) for driver updates as well.
Good Luck