Blackberry Sync Issues

I have recently come across a problem with calendar sync issues since upgrading my exchange server from 5.5 to 2003.

The problem only seems to affect users who have a blacberry and delegates to their calendar. If you remove the delegates or the blackberry from the equation then the problem no longer occurs.

When these users try to sync the calendar from exchange to the blackberry it is sometimes missing appointments that are displayed in outlook. Also the delegates sometimes have completely different appointment in their view of the users calendar.

I was wondering if anyone had experienced similar problems or new of a resolution for this one??