I did some searching on this forum.... Searched for 'quitting X' and found this thread -
http://www.linuxquestions.org/questi...ght=quitting+X
Try
Ctrl+Alt+Backspace. If it doesn't work, read all the messages on the thread or do some more searching.
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Oops! Sorry, most of this stuff had already been told by trickykid! I took too much time to post this message, during which he posted his reply.