OP, I don't want to see this turn into a Norton/Mcafee hate thread, but do this:
Uninstall (or try the best you can, might need Revo Uninstaller to completely kill it) Norton and try out Avast or Avira, two great free programs ( I use Avast myself) before paying for a new 1-year subscription.
Not only are the free ones good, but you'll more than likely see an improvement in overall speed, especially at times when it feels the need to do a complete scan when you're in the middle of something. If you still don't feel safe, then pay for your peace of mind.