When I installed NIS 1.4 for MAC I tried to enter my new product key, but it said it was invalid. I then tried to remove all the existing NAV/NIS applications and re-install, but then the installation failed. I still have NAV somewhere on the machine, since it pops up to scan the DMG installer. How do I cleanly uninstall the rest of NAV/NIS so I can succussfully install the new version?