This problem only occurs on versions of MainBoss before Version 4.0.
In order to start or stop MainBoss Service, you must make sure you have Windows Administrator privileges. Furthermore, on Windows Vista or Windows 7, it's not enough for you to have such privileges on your login name. When you start up MainBoss with the intention of starting or stopping MainBoss Service, you must use Run as administrator to make sure that MainBoss can use your administration privileges. To do so, right-click on the MainBoss icon (or its entry in the Programs menu) and choose Run as administrator from the resulting menu.