Listener--
#1. I hope your trial of MC is meeting your expectations, and more. For me, MC is the only choice for large libraries.
#2. As far as I know, AVG is the name of the product. I found it by searching download.com, which is also where I found MC, originally. I would recommend download.com for info on AV (antivirus) software as well as anti-spyware (no abbreviation in common use) software and firewalls.
You'll find that Norton is very highly rated, along with AVG and a couple others. My switch FROM Norton was due to the kind of issues that you're having. The AVG auto-protect is a lighter process, although a slightly less comprehensive one. The issue seems to be "heuristic analysis", a fancy way of describing stuff I don't understand. The upshot is that AVG relies more (although not entirely) on signature comparisions, whereas Norton sniffs everything (repeatedly) for what it views as suspicious behaviors, or opinions.
#3. While you're there, check out anti-spyware protection, a close cousin of AV (antivirus). Spybot and Adaware are the top-rated products, both free. I run a spyware check once a week, although I do NOT autoprotect. To me, the best protection is staying away from free music or porno sites. Well, for sure the free music sites.