Into the office this morning to discover that my mouse was limping again. The web has a number of hits for the problem, but nothing that's obvious. Now that I'm running 2 X servers, I was able to confirm that it hit both of them, and that there's no obvious connection with CPU time, though it's possible that some single process might be sucking it. Today I restarted both servers, not without difficulty: another issue is that the mouse is completely inactive when I start X, and I have to do it yet again. This is anything but reliable. Next time I'll try stopping individual processes to see if it improves things.