I'm not going to re-read all of the above posts from merged threads, but I think you're getting to the desktop background with no panels. Right? That has been discovered to be caused by some dual monitor setting in the Gnome Control Center. I don't use Gnome and so can't say exactly what. But I know it's at least a possibility. And I know how to bring up the Gnome Control Center without panels. And whatever it is in there that needs attention, it's been obvious to other people once they got in there. See here for something to try....
http://forums.fedoraforum.org/showthread.php?t=258252
Linear Mode
