I have searched through TechNet and came up empty. We have a problem using the OWA 2003 calendar to add new appointments, process fails after trying to save the appointment with a " The appointment can't be opened" message. This seems to be a certain backend server that has the mailboxes that are giving the problem, other user mailboxes located on different backend servers can use the calendar in OWA just fine. All is great using the outlook 03 client though. The only recent change to this backend server was a Dcom security patch. Has anyone seen this before? Thanks. Ariel