I haven't found the cause of this problem, but I do now have the fix.
* Go to the Intellisync folder which is located in the following location:
Windows ME, 2000, XP
C:\Documents and Settings\"profile name"\Application Data\Research In Motion\BlackBerry\Intellisync
* Locate your PIN folders in this location, specifically your PIN# folder and PIN#.cfg folder.
* Verify that Desktop Manager is not running. If it is, exit the program and then delete these two folders.
* Once deleted, start Desktop Manager and connect your BlackBerry device
***Note: This next step will remove ALL entries from the BlackBerry address book. Please ensure there is nothing in the address book that is not in Notes, or you have a backup of the BlackBerry.
* Open the Backup and restore program, click the advanced button, highlight the Address book database on the left, and click the clear button.
* Once the database is clear, close the backup and restore program, open Intellisync, and then resynchronize.