screen resolution problem - desktop moving
 

I've been using dual monitor set-up with no problem until today. Now, despite both monitor's being set to 1600 x 1200, the second monitor does not display at 1600 x 1200, and the desktop background moves as I move the cursor, and the cursor actually moves off the screen. I can't figure out how to resolve this. Any help would be appreciated.

Thanks,
Al