Try clicking on Support - Get Support to run Autofix to check your Norton installation and fix what it finds.
If that does not help, there may have been some corruption of your product. Downloading and running the Norton Removal and Reinstall tool should get you a clean installation of your product. www.norton.com/nrnr
After running NRNR, be sure you run LiveUpdate manually a few times, rebooting as necessary, until no updates are available