The Desktop Has Hung-What Do I Do?

In the rare situation that the desktop hangs, first try and restart it by pressing Alt-Ctrl-Backspace at the same time. This kills and restarts the X server. Another method of killing the X server is to press Alt+F2 to jump to a terminal, log in, and then run this command:

foo@bar:~$ /etc/init.d/gdm stop

This command stops the graphical login screen, which in turn stops the X server. You can restart it with this command:

foo@bar:~$ /etc/init.d/gdm start