Just a personal view,
I would first go to: Norton Removal Tool, (via Google), same again for McAfee and uninstall both products.
Then,
www.finalunistaller.com to clear out the remnants, then go back to Google and download the free version of
Microsoft Security Essentials,
Make sure both Norton and Mcafee are cleaned out first as MSE doesn't like other anti-virus programmes.
My 2cents worth. (Self taught home user, not a pro.).