Until recently, Calendar, Messages and Contacts were syncing fine with
Exchange 2003 (SBS configuration). Now only Messages and Contacts are
syncing, while Calendar is no more. As a matter of fact, calendar syncing
process starts and finishes, but calendar on the phone is empty. Syncing the
calendar with the local PC does work however. Exchange SP1 has been
installed recently, but I'm not sure if this upgrade trigerred the problem.

Server Specs SBS 2003