Database Maintenance  

In the Main Menu, under Tools | Misc Tools, select Database Maintenance:

If it tells you that you have a corrupted table, see the Corruption page. If it tells you that a patient has an insurance plan with no carrier assigned, go to the Family module for that patient. You might have to use the dropdown list by the Add Insurance button to view all plans for the family, because the plan in question might not be visible on the main screen of the Family module if it's no longer in use.