Norton Internet Security error 8504, 1404 is something that usually follows a severe corruption of the Norton installation files. Symantec (Norton) usually try to take you through the repair route but I have found that the best way to repair this problem is to uninstall then reinstall the latest version. It’s quicker, easier and ultimately more reliable.
If you have an older version you can also qualify for a little-known free upgrade to the later version. So uninstall your corrupt version using the “Add/remove programs” button in control panel (it’s under “Programs and features” in Vista and Windows 7). Download the latest version of Norton from your Norton Account or their Website, then install it with your older version’s product key.
Alternatively, if you have a short time left to run on renewal you can simply upgrade to a better Norton product like 360 at a cheaper price.