And... here I am.

The problem is solved. After thinking about it for a while, I came to the conclusion that it was not a Windows problem. If it was software, it would have to be a BIOS problem. If it was hardware, then it was just a matter of isolating which device was causing the problem.

I got my gardener to help me pull my hutch out from the wall so I could access the back of the tower case. I disconnected every USB cable connected to the case itself, thus turning off ALL USB services. I disconnected the data cables going to the USB hubs even though the other ends of those cables were disconnected at the computer.

Then I took a known-good USB cable, plugged into one of the USB ports on the front of the tower case. I connected it to my Kindle... and bingo, it connected instantly. I then frantically selected the fifty-three books I had acquired on the computer since the USB failed and uploaded them into the respective Kindles. They were nearly evenly spread between my Kindle and SWMBO's Kindle, but our reading tastes are so different that only five of the books went into both Kindles.

Then it was time to troubleshoot and find the device that was breaking the USB. It turned out that all of the devices were good, the problem was a defective cable connecting a USB hub to one of the devices. This was a fancy cable with electronics built into it so that either end of the cable could plug into the appropriate socket right-side-up or right-side-down.

I found out that just plugging it into a USB hub without even having anything connected on the other end set off all the bells and alarms and killed my USB. Unplugging it from the hub restored the system.

Quite an adventure, caused by a trivial link in the chain. Who woulda thunk it?

tanstaafl.