Is it your new one with Vista or Wndows 7?

power button shut down info - I didn't have time to read them so not sure which to suggest..
http://www.google.com/search?q=doing...ient=firefox-a


Did you try CTRL/ALT/DEL to get the task manager open ?
maybe google anything running that you don't recognize and see if something got in there to stall /hang up the machine.
there's also a shut down tab there to unless they changed it all from XP that I use.