This error message suggests that the system believes the user you are logging in with, is still connected somewhere.
Please ensure that no one is logged in to TaskCentre with these user credentials from their own machine and that there are no other servers running TaskCentre which might be using this log in.
Once you are satisfied that no one is genuinely using the account, then you can restart the service:
Log on to the server where the Orbis TaskCentre is installed.
Open up Control Panel and then Administrative Tools (steps to find these will differ depending on operating system).
From within Administrative Tools, double-click on Services.
In the window that opens, find the service called "Access TaskCentre Server".
Right click on this and select "Restart".
A loading bar will appear on the screen while this is happening and will automatically close when the service is running again. "Running" will then show in the status column to show the action has been successful.
If this doesn't solve your issue, please ensure all TaskCentre windows are closed and then open Task Manager and close all process that starts with "IWTS".
Finally, if you are still having issues, you may need to reboot the server fully which will refresh all connections.