When you rebuild the Preferences file, be sure to rename the Act Data folder. You will need to end all running ACT and Sage processes from the Task Manager first, then reboot your machine. The steps are in the section for the Alternate Method in Knowledgebase article 14770.
Note: Effective 6/1/13, Sage no longers provides support for the Act! software. This is now provided by Swiftpage.