Are you
sure?
We use AVG at work to protect our user PC's and it's been great. I personally like
Avast, which is also free for home users. They both do what they're supposed to do, I just like Avast a bit better because it seems to have almost no impact on system performance.
But Norton, no, I'm not a fan. I won't have anything Norton on my machines. I've experienced more problems caused by Norton than solved. I've had the exact same experience as the OP. I've had to rebuild several PC's due to Norton's attempts at fixing/speeding up a machine.