I have Norton Antivirus Through a Service Provider, NAV Engine- Won't Update Why is this?

 Howdy, I have Norton Antivirus through CenturyLink and when I update, Nav Engine won't update. I have downloaded and installed Norton Removal Tool and have used this twice and each time I reinstall Norton Antivirus it is the same thing everytime, NAV Engine won't update. I'm working on Windows XP. Is there a fix for this or is it just not ever going to update?