I have a user who does not want to have Tasks as a calendar in his iCal. Each time he deletes it from his iCal the Tasks calendar reappears. This user does not use Tasks at all it is completely empty.

This is not a local tasks calendar this is the one listed under his CalDAV Zimbra account in iCal with all of the other Zimbra Calendars he does want.

I have recreated this on a mac in my office with a test account.
Mac OS version 10.5.6
iCal version 3.0.6 (1273)
iSync connector version 5.0.2750
Server version 5.0.12

I have used the Zimbra admin console to remove the Tasks from the list of available features and the Tasks tab is gone from the Zimbra Web client interface. But it still shows up in iCal even after is has been deleted from iCal. Once the iSync synchronizes the Tasks calendar is back.

Any help is greatly appreciated. Thank you in advance!