Have you checked the Security tab on the Mailbox Store (ServerName) in question?
Run Exchange System Manager, then click on Administrative Groups, then First Administrative Groups, then servers, then (ServerName), then First Storage Group, then Mailbox Store (ServerName)
Right click on the Mailbox Store (ServerName) and then the Security Tab. See what Permissions are there.
A Second spot to check is Active Directory Users and Computers on the Exchange Server. You also have to have Advanced Features checked under the “View” header on the tool bar. Check any AD account’s Security Tab, as you mentioned she has access to ANY mailbox…
Let me know if you find something…
Also, is there a group with exchange admin privleges which she is a part of? She may have been added to the wrong group by mistake. Do you have any groups listed as exchange admins?