Twice in recent weeks, I've experienced a weird phenomenon when running 
under xorg.  The cursor jumps to the left edge of the screen.  If I 
move the mouse slowly, I can get anywhere; if I move it too rapidly 
(i.e., at normal speed), the cursor jumps back to the left.

It's not a hardware problem; one of the times this happened, I plugged 
in a USB mouse and got the same behavior.  It's happened twice thus far 
on my laptop in the last 4-6 weeks; I've never seen this before, 
including on my desktop machines which also run -current and xorg.

I have not found a fix short of exiting X and restarting it.  Switching 
to text consoles and back has not helped.

I'm running xorg 6.8.2 and twm with -current from about July 1.  

		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb