Is this reproducible by anyone?
1. open a single gnome-terminal
2. log in as root via "su -"
3. run gedit
4. try to open gedit's Preferences via the application specific menu
displayed on the top panel (does it open? here, it doesn't)
5. try to trigger the "Activities" hotspot with the mouse
What happens? Here the desktop freezes completely. One can still move
the mouse, but that's all. Killing gedit and gnome-terminal doesn't
achieve anything. If killing more processes, eventually the "Oh no..."
screen appears, but upon trying to log back in at GDM, the desktop
doesn't load.