In Screen Saver, when I move Mouse to get to desktop the screen scrambles ...

[mahesh]

In Screen Saver, when I move Mouse to get to desktop the screen scrambles ... I have to mouse click on the Desktop to unscramble the screen.
Not a show stopper, just annoying.

Got any ideas as to the cause?
I am using Compiz and a Radeon video card.
Carl
My other hobby is antique Radios and TV restoration.