In case somebody wants know
After 3 hours with Microsoft Support - here is what we came up with...
Problems with the Cached Exchange Mode (CEM):
Make the profile Roaming…
Open Outlook in the Online mode (NOT CEM)
Export to a local file such as C:\temp\User.PST
Quit Outlook
Go to Exchange Admin and remove the mailbox and run the cleanup agent.
Go to Active Directory Users and Computers and start Exchange Tasks and add
a mailbox for the user.
Go back into Outlook and import the file into the NEW EMPTY mailbox.
Quit Outlook…
Delete the Mail Profile (IDOC.PRF)
Create a new Mail Profile(IDOC.PRF) and use the Cached Exchange Mode – make
sure the OST file is pointing to the right location.
Make the Profile Mandatory…