If you find that you can’t RDP to a 2008 R2 Server after installing SP1 then this is most likely due to a Microsoft hotfix causing this issue.
Log into the console and uninstall hotfix 2667402 and then reboot and all done.
If you want to do it remotely then load up powershell and do the following command.
wmic /node:SERVER process call create “powershell wusa /uninstall /kb:2667402 /quiet /forcerestart”