Comment 12 for bug 402892

Yep, "pkill nautilus" from a text terminal (press Ctrl+Alt+F1 together to get a terminal or use an existing one on your desktop if you can via Alt+Tab/guake/other, once you have one logged in, type the pkill command mentioned earlier, then use Ctrl+D or type "logout"(enter) to log out of terminal; then press Ctrl+Alt+F7 together on this ubuntu version to switch back to the graphical mode) fixed it.