I replaced my Kensington Expert Mouse under the 5y warranty, but before downloading and installing the latest version of trackballworks, I took a "snapshot" of my system (took about 2 minutes).
When I tried to open the software to make settings, my system froze. Restarting did not solve the problem.
Solution: Rollback the system to the snapshot and--voila!--up and running in about 2 minutes.
Many thanks, alaskamovieguy:
http://muvipix.com/phpBB3/viewtopic.php?f=4&t=7061&p=63061&hilit=rollback+rx#p63061