Cannot view MPEG video files

Interesting and frustrating video problem….
I never had any problems playing MPEG video files until recently….(Use Windows Media Player 7)
Now all I get is a split second glimpse of the video and then the screen is blank, audio is OK.
When IRight-Click the blank portion and the context menu appears, I can see the video behind the context menu.

Now I discover that I have the same problem with DVDs.
I have used many players for MPEGs, but the Windows Media Player is my primary.