I found a solution for this that worked reasonably well for me - I deleted the IntelliSync user data folder from your Windows profile, and then the next time I connected the Blackberry, it was like the very first time - I just had to re-setup the connections to Outlook, and then it sync'd with no errors. The folder I deleted is located here, by default:
C:\Documents and Settings\<username>\Application Data\Research In Motion\BlackBerry\Intellisync