Video window in CS5 goes blank
 

Hi - my edit system - Adobe CS5 has started misbehaving. During an edit, the monitor window went blank. everything works fine, but no picture. Only shutting down the PC and restarting cured it. It did it again twice in the 3 hours or so I was editing, and it's never done it before. Anybody have any clues - I shall try downloading new drivers for the graphics card, just in case - but as it's always been good and stable before.

Very strange.