Offline Address Book Fails to Download in Exchange 2010

I found that this was caused by the configuration of the redirect changing the security permissions on the web.config file within the OAB virtual directory.   To fix the problem, browse to the OAB virtual directory and re-add the authenticated users group to "read" and "read and execute" permissions on the web.config file.    

Here are the corrected permissions:  

I hope this helps everyone out!