I have a stumper of a problem running Outlook 2002 on XP SP1 & SP2 with Exchange 2k with all updates. User A had access to user B's calendar with no problems via group rights. Recently (after no admin changes)user A complained that when they access user B's calendar they receive the typical "unable to display the folder". The security rights were checked on user B's outlook and all was fine. Other user's access to user B's calendar has not changed either. Here is where the problem shows up. I manually added user A (mailbox and calendar only) to user B's rights. User A now has full access to user B's mailbox (contact, calendar, inbox...). Other users rights to user B's mailbox have not changed. Removing user A's rights from user B's mailbox made no change. Using exchange mailbox rights in AD to Deny user A from user B's mailbox makes no change. User A still has full rights to user B's mailbox and other users mailboxes. There is no way that user A should be able to access user B's account in any way. User A is only part of the users group on the domain and locally. If user A logs onto another computer, everything works as expected, ie only having rights to the calendar, etc. This problem has now showed up twice. The last time I had to change the users computers since they are setup with a SOE and deny the user from logging in to the old computer. I have reinstalled Exchange with service packs with no change. I have removed and readded the computer to the domain. I have resetup the profile for the user with no change. If anyone has any suggestions, I would be eager to try them as this problem will not be limited to one computer and I don't want to do a domain reinstall just yet.