Sat and read an article about Wikileaks and I have hung completely Ubuntu. Did not work, even Alt+SysRq combinations. After reset, first launch X s flashes screen state in the form in which it was to hang — Chrome open Hebrom. Interested in the question where it comes from? A similar effect is also observed when switching accounts: before request of the password at the moment displayed the user's desktop to which you switched in the same condition in which it was before the previous change of account.