This can be resolved by restarting the TaskCentre Server Service.
Follow these steps to restart the server service:
Log on to the server where the Orbis Task Centre is installed
Open up Control Panel
Open Administrative Tools (steps to find these will differ depending on operating system)
Double-click on Services
In the window that opens, find the service called "Access TaskCentre Service"
Right click on this and select "Start", or if that is greyed out, 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.
To prevent this happening in future, ensure that you have disallowed time set against the period that Maintenance runs in and the period before. This will prevent Maintenance being delayed by tasks still finishing and then not able to complete in its dedicated time slot.
This can be done in TaskCentre under Tools, Options, Run Times and Maintenance