If you see a slew of 10016 errors in event logs, first try this:
http://support.microsoft.com/kb/920783
and then try this:
http://halfloaded.com/blog/sbs-2011-distributedcom-eventid-10016-fixed/
If you have to authenticate three times — once for for the portal, twice for RDP — try this:
http://tsbraindump.blogspot.com/2012/02/sbs-2011-remote-web-workplace-login.html