The BITS service provided job credentials in response to the UNIDENTIFIED authentication challenge

I receive the following Windows 7 event log error every time that I either turn on or restart my computer and open Outlook 2013.

I am running Exchange 2010 on my server which is running SBS 2011.

The BITS service provided job credentials in response to the UNIDENTIFIED authentication challenge from the remote.xxxxxxxxx.com server for the Microsoft Outlook Offline Address Book 9a413502214705448473c1211a339e7b transfer job that is associated with the following URL: /OAB/72b5bfc4-efec-4564-aa98-23906d1a79d2/oab.xml.
 The credentials for the S-1-5-21-1181636421-3260534386-1882037235-1164 user were rejected.

Does anyone know what this means and how to best resolve it?

Thanks

Howard