If you activate the options "DontVTSwitch" and "DontZap", and start an X Server with no clients running, you may have to turn off your computer. If you do have an X terminal running, typing "kill -9 [PID of the X Server]", your computer would lock up. It won't lock up if you just type "kill [PID of the X Server]" or "kill -2 [PID of the X Server]". However, even if you don't activate the options "DontVTSwitch" and "DontZap", "kill -9 [PID of the X Server]" would still lock up your computer.