Hello, I am having a similar problem.
When I shut down my computer last night, it displayed the familiar "Do not turn off your computer, installing update X of 6" screen. As usual, I left it to instal and shut down by itself, and I went to bed.
When I got up this morning (about 8 hours later), I noticed that my computer had not shut down (though the screen was black). I wiggled the mouse, and it immediately woke up to display the same screen (now on 6 of 6). If I leave it alone, the screen will black out again in about half an hour. I do not seen a cancel option, and do not have a cursor anyway.
I have Windows 7 Home Premium (64 bit) on an HP laptop with a Athelon II P(something) 2(ish) ghz processor. Sorry, I don't remember what processor it has exactly and there is no sticker on the laptop itself. I cannot check the specs on the computer itself because I cannot do anything on it.
I have noticed that the two periods at the end of the "Installing 6 of 6.." message are still slowly moving across the screen and back, and there is a spinning wheel to the left of the message that might be my cursor, but it doesn't respond to my mouse or my touchpad.
Does anyone know what I should do?