For the vast majority of server maintenance I perform for my clients, I use Remote Desktop. I recently ran into a frustrating and confusing issue on two servers running Server 2008 R2, following the installation of Service Pack 1. I could no longer connect via Remote Desktop. It appears as if it's about to connect and then bombs out.
Basically it turns out that there is a problem with Microsoft Update KB2667402 which has since been corrected and re-released. If you have the same problem you will need to uninstall that update, reboot then reinstall the new version.
If you can't remote desktop to the server but are able to use WMI commands to it, you can use the following command to uninstall the update:
wmic /node:<SERVER> /user:<USER> process call create "powershell wusa /uninstall /kb:2667402 /quiet /forcerestart"
Otherwise of course you will have to access the server via the console, or via other means - e.g. logmein/VNC client.