I fixed the problem with all the USB stuff. Apparently Windows associates a device with the USB port where it is attached (Linux doesn't do this with the mouse, but I don't know about other gadgets). When I moved the computer, I disconnected all of the USB devices, and I probably didn't plug them all back into the “correct” ports. Starting up the computer, logging on, and plugging the components fixed the problem.
So I now declare Hal's Evil Twin fixed, and I'm going on to other things, such as installing Ubuntu Feisty Fawn as a dual boot on HsET.