Yes it happened with me when I installed RC2, i tried for about half hour to get online but despite gateway and host reachable(cable internet) I couldn't autheticate myself to surf web. Then only out of frustation I just restarted my PC and poof I logged in a sec . This happened every time I started after 2 or 3 hours. Don't know any specific reason for as Now I only have SP1a installed.
I think problem is with that BITS thing that is part of SP2 because my problem started only after I applied that patch.