There is a bug CSCsa80702 on unity version 4.0.(4). This usually occurs after installing Windows 2003 SP1.
Workaround options.
Once Unity 4.0(5) releases, an upgrade to Unity 4.0(5) will resolve this issue
Other options for workarounds:
1. Uninstall Windows 2003 SP1 from the Exchange 2003 server. Once this is complete the Unity server must be fully (Windows) rebooted.
OR
2. Place the UnityMsgStoreSvc account (the account the AvMsgStoreMonitor service logs on as) in the local Administrators group on the Windows 2003 SP1/Exchange 2003 server. Once
this is complete the Unity server must be fully (Windows) rebooted.
If the Windows 2003 SP1/Exchange 2003 server is a clustered Exchange server place the UnityMsgStoreSvc account in the local Administrators group for all nodes in the cluster.
Once this is complete the Unity server must be fully (Windows) rebooted.
If the Windows 2003 SP1/Exchange 2003 server is a domain controller it is not recommend to place the UnityMsgStoreSvc account in the Domain Admins group because this group has explicit denies be default on all Exchange Message Stores. Placing the account in that
group will allow Unity access to the Services Control Manager so Unity will be able to 'see' the Exchange server again but all mailbox logins will fail. Instead do option number 1 -- uninstall Windows 2003 SP1.
How can I add UnityMsgStore to the Local Administrator groups?
Thanks