Some versions of Windows incorrectly report that the firewall is off when it's actually on. Specifically, suppose you go to Windows Firewall in the Windows control panel. Your computer will respond with a window that tells you whether the firewall is off or on, as set by the last time you used this window.
However, it is possible to turn the firewall off/on using other windows. In particular, you can turn it off or on using the Services window (obtained by selecting Manage on Computer or My Computer). If you turn the firewall off or on using the Services window, the other window (accessed through the control panel) doesn't change.
As a result, the firewall may be on, even though the control panel says it's off. Even more confusing, the firewall typically lets people with administration privileges access the MainBoss database, whether or not firewall permissions have been set up appropriately. Therefore, you may find a case where administrators can access the database just fine, but others cannot.
If you find yourself in this position, go to the Services window and make sure that the Windows Firewall service is actually in the condition you think it is (stopped or started). You may need to start or stop the service in order to put it into the state you actually want.