Open Computer Management by right clicking Computer (on your desktop) and select Manage.
In the left pane of the window that opens click Services and Applications, Services.
In the centre pane scroll down until you see Firebird Server - Magix Instance, double click it to open the properties window of this service.
The Startup type is probably set to Disabled and the Service status says Stopped.
Change the Startup type to Manual.
Ok the change and close the Computer Management window.
In AVG you will have to find the option which determines which services are diabled if not used frequently and turn it off or put an exception in for Firebird Server.