Sometimes in you find yourself in the middle of a graphical meltdown, all of a sudden the restart X shortcut for Ubuntu is your best friend! Otherwise you find yourself trying to drop out of graphical mode into a terminal user. Or heading straight for the power button!
So, what is the restart X shortcut for Ubuntu?
For a long time the restart X shortcut was:
Ctrl + Alt + Backspace
This helped many people out of a bad spot. Graphic capabilities were limited in them days and hang ups were more common. Hardware and Linux distributions have improved since and become more stable since then.
Since Ubuntu 10.04 this was changed to the lesser known shortcut:
Alt + PrtScr/SysReq + K