Well, I'm not surprised that Norton was the cause of your troubles, I don't know if you are running Mac or Windows, but at least for Mac it uses lot of energy, and has not much efficiency... I do run an AV programm, since I send some time some mails or else to friends on Windows, and don't feel like sending them some extra creepy-crowlies... I sent recently to a friend, a DVD with some downloads (from gnutella), done by mistake, since they where wrongly labelled "for OS X" and inspite of being compressed as dmg when opened, were containing some text and an exe.
I scanned that with Norton before to send it. When that friend opened that DVD, the whole PC flickered with alarm... "you have so many seconds to shut your PC of !"... Back home, I scanned the DVD again with Norton... nothing : clear as a babygirl breath.
Having lost my confidence in Norton, and knowing that it some time had damaged some macs, I decided to change to another one, apparently very efficient, and which, inspite of being totally free, did a constant updating of hes virus files : ClamXav... Well, scanning that DVD revealed 23 instances of the same Troyan, hidden in exe files.
So, it confirmed totally, at least for Mac, what some had being telling me about Norton.