Okay, so you are definitely in a stuck situation. What I would do is try and see if I can get that software unstuck by tricking it. Yes, we're dealing with milliseconds as it cycles through the first steps after the power is applied, but you might just get lucky.
What I would try is to hit the power switch and then about a half a second after you start to see any sign of life hit the power switch again. I doubt you can break anything but you might just catch it in such a way that next time you hit the power switch it can be put into safe mode.
So here it is again, in full.
'A' -- Hit power switch. Miss Stubborn shows signs of waking up and hit power switch. Miss Stubborn goes back to sleep.
'B' --Hit power switch and start tapping the F8 key and see if Miss Stubborn throws her Windows Update tantrum. If she does, turn off and go back to 'A'.
I'd repeat that a few times until you are kind of sick and tired of it all.
By the way, disconnect the Net cable to Miss Stubborn, if you haven't already.