NAV service won't start after loading fob. Getting extensions error.

Dybs

So after restoring a database and setting up NAV service and all working ok. I imported a fob with lots of object changes and now the service won't start and I get an error in the event viewer that seems to relate to an extension : The application object of type 'CodeUnit' with the ID ####### is defined in the app *************** but already exists in the base application. I haven't used extensions much and not sure what if there's anything I can do to get service running. I'm not really interested in the functionality coming from the extension; I just want to get the service running. Any ideas please?

Dybs

Update: service starts but crashes when trying to connect on the client. I have found that by removing the controls etc the extension is trying to add I can get the error to move along but there are so many of them! Is there a way to stop the extension changes from trying to apply?