Monitor RDP howto help

Did a bit of searching on this but did not find really what I was looking for. !sad

Scenerio: So we have thin clients for case manager work rooms in a couple of our offices. This morning after a scheduled reboot to update some things on a server in san antonio terminal services came back up, and the port was open but the RDP connections were getting refused.

As far as I can see this will be tricky to monitor as if I were watching for the service it would have shown up OK, and if I were checking to see that the port was open that as well would have been ok.

Does anyone know of a plugin or solution that would actually check to see if the RDP requests were getting declined?

Thanks in advance.

-Jimi