One option is to try deleting that right panel.
Another is to delete 5 folders from your profile to reset your entire GNOME settings to default:
You can do it with following command (once you are inside your home directory:
rm -rf .gnome .gnome2 .gconf .gconfd .metacity
but do it while you are logged out of the GUI.
You can also try to mess with mentioned folders and if you fail, to delete them as the last option.