Personally, I use 'Avast' and have never had any problems. It's free, it updates on a regular basis (sometimes 3 or 4 times a week), it scans email and websites.

I teach and assess IT Technicians, as well as buliding and repairing computers, and I always install 'Avast' in preference to Norton or McAfee. They cost money and you have to buy updates every few years.

AVG or Avast are better options - and they're free!