Something similar happend to me.
My sister froze up a game for saving it 3 times in 30 second, and when I was able to Ctrl - Alt - Del, my monitor turned to standby mode. So I turned it back on again
and the little light was green, but then it made a *Click* and it went into standby.
And I HAVE to shut off my computer by pressing Turn Off in the start menu, I just can't click the little power button on the computer, so I turned off the breaker switch, turned it back on adn, Voila.