I have a PC (Windows XP) that is used for one of our road warriors. For months, there hasn't been an issue with her connecting. Over the last week or so, it seems that I have to reboot at least a couple times a week or she gets the generic "Can't connect to the remote computer" error. If I reboot the machine, it works fine but then it seems that it doesn't terminate the session when she disconnects.
I've also verified that it's not only her that is unable to connect - if she has the problem, I can't connect remotely, either.
The last time, I was able to log in locally and verify that "Terminal Services" was still running. I then logged off and she was able to connect normally.
I advised her to make sure that she was logging out of the machine, as opposed to simply closing the RDC connection (which, she admitted is what she had been doing previously), but that hasn't made a difference.