I order to prevent all your terminal service sessions being used and thereby blocking access to a server, tsadmin can be used to log users off remotely or session timeouts / limits can be imposed.

Add the following Registry entries, creating a 1 hour disconnected session limit and a 2 hour idle session limit:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Control\\Terminal Server\\WinStations\\RDP-Tcp]

To add the entries save as whatever.reg and double-click.