You have a shared mailbox on a Microsoft Exchange Server 2007 server. The corresponding Active Directory user has the userAaccountControl attribute configured. You run the Set-mailbox cmdlet to convert this shared mailbox into a regular mailbox. In this situation, the userAaccountControl attribute resets and the original value is lost. Therefore, some unexpected issues occur.
For example, the original value for the userAaccountControl attribute is '’0x40200". After you run the Set-mailbox cmdlet on the shared mailbox, the attribute resets to "0x200". This causes remote logons to fail.