Arg. And it's still like this after a clean reinstall of the system which did not fix the problem. I also tried many other things which have been of some use in addressing this problem in the past, none of which worked this time.
This computer is Tekserve bound, I think.
UPDATE: Tekserve quotes four business days for the repair; the were tremendously nice and the thing is still under warranty.
Um, and yes, that is Ganesh, the Elephant God riding a mouse, sitting atop my monitor. He is ostensibly the remover of obstacles, a good god to have sitting on a computer, I think.