We have an Exchange 2003 sp2 / Windows 2003 sp2 enviroment.
I have a user who is getting items deleted from her Calendar, i have checked the obvious things like other users permissions on her mailbox / Calendar and they only have reviewer, nobody other than admins have permissions over the object in AD.
The user creates a metting request and then sends it out, then next day its gone. She proved to me in her sent items that the request was sent.
Im out of ideas, anyone else got any.