I have had good success with this approach. Database retains all functionality while hiding the ribbon and not allowing the user to manually display the nav pane.
Note: It's still possible for a user to turn on the nav pane in an MDE/ACCDE front end. Running as runtime prevents this.
Method to force DB to run as runtime is simple: Create a shortcut (or modify the existing one) and in the "Target:" line add /runtime between the path to your access.exe file and the path to the MDE/ACCDE file.
It would still be possible for a user with just about enough smarts to be dangerous to do damage if they modify the shortcut, remove the '/runtime' and run the database that way, but IMHO that would be a deliberate action to circumvent security measures in most companies would be subject to disciplinary action. (In the one I'm contracted to at the moment it's grounds for instant dismissal!)
HTH,...Jon.