Here's how to do it manually, by deleting the history file:
- If you haven't done so lately, make a backup of your iCal calendars (iCal File menu > Back up iCal)
- Quit out of all open programs
- Make sure that nothing is syncing (Spanning Sync, .Mac, iSync)
- Move this folder to the trash: ~/Library/Application Support/ SyncServices
- Open iCal and give it a few minutes to write out the new database ...
This worked! No errors. Now, to iCal...
"Your calendar information is being reset..."
And it works! Sweet!