Configuring time out on disconnected sessions is limited to value from 1 minute and on.
In order to set the time-out limit to seconds follow this procedure:
1. Open Terminal Services Configuration < RDP-Tcp properties < Sessions
2. check the "Override user settings"
3. Mark to End a disconnected session as "Never"
4. Start < regedit < navigate to this key:
5. Double click MaxDisconnectionTime value and set it to X000 decimal. replace X with the number of seconds you want.
For example : 4000 will be 4 seconds.