> Occasionally my cursor goes wild and generates a continuous key down
> event, like holding a key down until it repeats -- but once it
> starts, it never stops. I have to shut down and restart my computer
> to stop it.

I haven't seen keyboard problems, but my mouse has been known to go wild,
jumping around and clicking at random all over the place. The problem turns
out to be dog hair in the mouse's LED aperture...just one strand was enough
to cause chaos!
    
Maybe your keyboard's dirty?
    
- John