This may help. From the Wacom support knowlegebase:
Is it possible to delete all the tablet preference files at once?
Yes. With the installation of latest tablet drivers on OSX 10.3 or later, and Windows XP or greater, a separate tablet preference file is created for each user account. It is possible to delete all the tablet user preference files, as well as the common tablet preference file used at login, at the same time. Follow the steps below to delete all tablet preferences.
In the Finder, from the Go menu select "Applications"
Select the "Wacom Tablet" or "Pen Tablet" Folder in the applications list.
Open the Preference utility and select Remove all preference files.
You will need you Operating System password