Are there known policy settings causing unexpectedly terminated RDP sessions to be logged off - Event 551
- by bernd_k
http://msdn.microsoft.com/en-us/library/aa383015(VS.85).aspx states
When a user's session is unexpectedly terminated by a network or client failure, the user is disconnected but not logged off.
But since we got a new system administrator who installed some policy to terminate disconnected sessions after some hours, I never again could reconnect to to an unexpectedly terminated session (usually VPN problem)
I found the following link which shows a similat scenario.