Appointments go missing after Office 2003 SP* installed

We have a serious outook 2003 problem since we have installed office 2003 SP3.
Whenever you enter a new appointment then the entry gets lost after
synchronization with the exchange server 2003. All other office programs work
fine.
Following error messages we find in the Synchronization folder:

14:24:21 Synchronizer Version 11.0.8161
14:24:21 Synchronizing Mailbox xxxxxx
14:24:21 Synchronizing local changes in folder 'Kalender'
14:24:21 Uploading to server xxxxxxx
14:24:22 Error synchronizing message ' yx xyc<xcy<cxyy<cxx'
14:24:22 [80070005-508-80070005-323]
14:24:22 You do not have sufficient permission to perform this operation
on this object. See the folder contact or your system administrator.
14:24:22 Microsoft Exchange Server Information Store
14:24:22 For more information on this failure, click the URL below:
14:24:22
http://www.microsoft.com/support/pro...8-80070005-323
14:24:22 Moved a message that failed synchronization to 'Local Failures'.
Message subject -> ' yx xyc<xcy<cxyy<cxx'. You can view this message in your
offline folder file only.
14:24:28 Done

Thanks for any help!
Cheers
Daniel