right clicking on start, going to shutdown or sign out, and choosing shutdown?
Dafydd.
PS. Didn't see your OS?
When I turn my Toshiba laptop on it comes up with a screen saying computer didn't start up properly need to restart but when you try to restart it just reverts back to that screen all the time... any help Please?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic