Well I am still battling this issue.. I looked up the docs you linked about the encryption, server 2008R2 does not have the exact settings but I found this for the security and set it on the domain policy.. http://xunyangit.wordpress.com/2011/02/22/the-biggest-thing-you-should-know-before-upgrade-to...

Since moving my movies and music from server 2003R2 over to a domain controller running server 2008R2 I am unable to connect to any SMB shares on that new server from my xbox.. It all worked very good on 2003 non domain controller, and now will not connect with an error of cannot "connect to sh...