Version: Illustrator CS5.1
System: Mac OS X 10.8.5
When I open Illustrator, opening the first document causes my panels to jump to the bottom of the screen, so they're nearly off the screen. If I click the button for my workspace, they return to their proper place at the right side of the screen. If I open another document, they stay where they are.
But it happens every time I open Illustrator and open the first document. It happens with every file, and with any custom workspace. I've created new workspaces and it hasn't solved the problem. I haven't found an answer on Google or in the forums anywhere.