This occurs when you have too many users logged into Medisoft. There are a few reasons that this will occur, the most common being that the current number of users exceeds the licensed amount. To remedy this try to get all users out of the Medisoft and Office Hours then go to your server and look at your Advantage Configuration Utility and see what the current users is at:
Open the table and if the current users are not at 0 then select stop service.
WARNING: Do not stop services if people are in the system and working as it can cause data corruption. Once the table clears select start service and have the users get back in.
Notice: On the newer version of Network Professional there is a mobile service available, if you continue to experience issues after restarting services this may have turned on by default and be requiring a license. If you are not using the mobile service you can open services by opening the services window and disabling the McKesson MSL Mobile service.