If a user can't log in because they appear to already be logged in, restart the TaskCentre Service to disconnect all active sessions. Follow these steps:
Log in to the server running TaskCentre.
Open Control Panel, then open Administrative Tools.
From within Administrative Tools, double-click Services.
Find the service named Access TaskCentre Service.
Right-click the service and select Restart.
If prompted, click OK to confirm that the Schedule Agent Service will also be restarted.
A loading bar will appear on the screen while these are restarting and will automatically close when the services are running again.