If you're still in your trial period ditch Norton and install some of the excellent free security software that's available. If you've paid, that's a different matter.
This post by skidzy is very informative; click here
I would choose Avast over AVG.
I ditched the 90 day Norton trial on the laptop I'm using after a week or so, it refused to scan more than 4 files and kept nagging me that a scan was required...which only scanned 4 files...so it nagged...etc etc