There are layers to be untangled here, no simple answer. Does this user have delegates in Outlook? Remember if a DELEGATE deletes an appointment from their inbox before it is accepted it will be removed from the user’s calendar. Also we have had multiple issues with using the blackberry to set up or accept meeting invites so we tell people to ONLY set up or accept appts from the outlook client and never from the blackberry. Also if you deleted the appt message from the blackberry it will disappear from the calendar as well. Do you really mean the meetings are CANCELLED, or are they just disappearing off the calendar?