Use Remote Desktop Connection to log in. This should allow access and let you confirm whether the problem affects the video on the remote PC. It may also permit you to view event logs to reveal more in depth information.
Another possible problem is that your server has experienced too many changes too rapidly and has decided that its registration is invalid. If that is the case, you may need to look up how to re-activate Windows Server.
But this happened back in 2007 and you should share the answer that worked for you at the time.