I tried a cold boot.
Well, it's a NoGo. The Toshiba banner comes up, and the screen goes blank, The little circle spins, and curiously the Internet access bars appear at the lower left, and nothing else
I will have to take this to BestBuy and Geek Squad immediately tomorrow morning to resolve. I seems to have something to do with fast boot. I hope this is something simple.
Update: Aug. 9
Geek Squad says the mother board died and the computer has to be sent to Toshiba in Kentucky. Why would an update fry the motheboard?
There had been a couple other problems -- the trackpad had gotten jerky, and the fan was seen to be failing. It might have overheated during the update process.