Due to the current instability with the GNOME environment, here are a few handy key chords to help reset the X windows server.
Press:
Control-Alt-Backspace To: Kill all running processes attached to the X-Server on the computer and restart the X-Server, Note: As this ends all tasks associated with the X-Server, only use this one if you just turned the computer on or know nobody is using it, though it is the fastest way to restart X and is the only key chord that has any chance of returning GNOME to a functioning state.
Control-Alt-F1 To: Take you to init-1 (command line), pausing the X server, but not disrupting any open processes. From this command line many smaller tasks can be accomplished, provided that they do not need a separate window to operate.
Control-Alt-F7 To: Bring you back to init-7, (resuming X), use after Control-Alt-F1 to resume the windowing server. You should wait roughly 10 seconds in between using the two commands or the X server will get a little confused. Note: This pair of commands will never bring GNOME back to life, but if you want to work on the computer you can use the init-1 environment to do many simpler tasks.
For more information, as well as a whole host more key combinations please see this website.
Additionally, if one of the computers refuses to cooperate, it is possible to ssh in to any of Linux computers from any *nix system on campus (either a lab Mac, another Linux box, or your own laptop for that matter). To do so type:
ssh -Y username@hostname.physics.carleton.edu
And then enter your password when prompted.
So, for example,
ssh -Y cerjanb@deneb.physics.carleton.edu
Would log me in (provided I entered the correct password) as cerjanb on Deneb.