In most Linux distro (including Ubuntu), the keyboard combo Ctrl + Alt + Backspace is often used as a shortcut key to restart X. However, in Ubuntu Jaunty, this keyboard shortcut was disabled, “to reduce issues experienced by users who accidentally trigger the key combo”, as quoted by Ubuntu.
I don’t know how many people will find this a welcome improvement in Ubuntu. Personally, this has caused me a lot of inconvenience as I always depend on it to get myself out of a nasty crash.
For those who wanted to restore back the Ctrl + Alt + Backspace combo, here’s the way:
Restart your computer
That’s it. You can restart your X using Ctrl + Alt + Backspace now.