Originally Posted by me

This has been going on for a while now, since Xorg 6.8... Every once in a while, my cursor just takes on a life of its own, flying all over the screen and clicking (right, left, and middle) on everything until I hit the Escape key a couple of times. The effect is almost exactly as if I were using the "mouse" driver with the wrong protocol, albeit temporary... But I'm using the right one (ImPS/2), and this happens with both the ordinary "mouse" driver and evdev. It also happens only with my A4Tech trackball, not with any other trackball or mouse I've tried.

Also, the cursor occasionally ceases to respond to any movements of the trackball. AFAICT, this can only be fixed only by unplugging the trackball from the PS/2 port and plugging it back in, with the machine of course being powered down during that procedure to prevent possible damage. I've tried restarting X and simply rebooting, but they don't fix this latter problem - the PS/2 connector *has* to be pulled out and stuck back in, no idea why. Again, this happens only with the A4Tech trackball, not with anything else.