Ok,
If you want to stick with v6 please download a fresh copy from www.norton.com/n360s_6 for the Standard Edition, or from www.norton.com/n360p_6 for the Premium Edition and save it where you can find it.
Download a copy of the Norton Removal Tool from www.norton.com/nrt. Save that too.
Export your ID safe data it you use it.
Uninstall N360 from Windows Control Panel and reboot. I would chose to remove all data.
Run your copy of the Norton Removal tool and reboot. It will not hurt to repeat this step.
Install your new copy of N360 and run Live Update, restarting where required, until no more updates are available. Import your ID safe data.
If instead you wish, you can upgrade to the latest version of N360v20 for free.. To do this you could use the Norton Remove & Reinstall Tool. First, export your Id Safe data if you use it. You can download that from here. Remember to run Live Update, restarting where required, until no more updates are available.
Let us know how you get on
Thanks,
Dave