I have seen a problem on multiple computers and heard of others with the problem when having a computer set all the time to duplicate the display onto either a projector screen or TV. The problem is that the duplicate display setting does not stay when either the computer goes to sleep mode or has been turned off and back on.

Commonly a laptop set like this comes up with a blank screen and no picture of the computer is displayed until the TV or projector is turned on and displays on the other device. The only easy fix is to disconnect the video cable of the other device or press Win-P to get choices on the screen.

I never had this problem with Win 7. It kept the display settings until they were changed.