If you don’t want to use a user interface to change the effect of Ctrl+Alt+Backspace in any flavour of Ubuntu you can follow these steps:
1) Install the “dontzap” package
sudo apt-get install dontzap
2) Open Terminal or Konsole and type:
sudo dontzap –enable
or
sudo dontzap –disable
Where “disable” means that Ctrl+Alt+Backspace restarts the xserver while “enable” means that it won’t.
