Error: Outlook Web Access was unable to access the Active Directory resource
Outlook Web Access was unable to access the Active Directory resource. This may be because the Active Directory object does not exist or the object has become corrupted, or because you do not have sufficient access rights for the object.
To resolve this error:
Follow http://support.microsoft.com/kb/938444 and ensure the Authenticated Users group has Read permissions on the organizational unit the affected user resides in.
Wait for replication to complete or force it…
If this one did not work, recreate the GAL as Exchange uses the ShowInAddressBook attribute to authenticate clients.
Once you create a new GAL, associate that to the Mailbox database, dismount the database and remount.
It should work…