it seems, that there is a conflict between navigator free and the app DB-Navigator. Both apps latest version, my device: SGS2 I9100, Android 4.1.2.
Navigator free was closed but there was a service of navigator free running in the background and, I had a notification to download newer maps.
I started DB-Navigator (which is for german railway), closed it, and afterwards I could not enter into internet. (GSM detached). No rebooting helped. I had to delete navigator free as well as DB-Navigator to solve the problem. I remarked, that I had hints before "navigator not working-stopped" as well as the icon of navigator free had changed to a simple green droid-icon.