My Mac Pro's Mighty Mouse has been replaced with a Logitech Performance Mouse MX.  This mouse is extremely precise and comfortable to use.  Had my Mighty Mouse's little nubby track ball not continually gummed up, I would have continued to use it happily.  Since the mouse...

Update: I believe I've zeroed in on the bad egg - Logitech's Control Center 3.1. I just started having the problem on my new powerbook after installing it. Numerous complaints exist: http://www.macupdate.com/info.php/id/8154 http://forums.macosxhints.com/showthread...