Probably the download random stuff thing. I never visit malicious sites, but I download a hell of a lot of certain kinds of torrents, which are notorious for being bundled with malware and shit. But it really doesn't hurt to install that stuff just in case. Ya never know these days :\
But yeah, so AVG 8 works perfectly fine on my parents' computer, but not mine. It's god damned frustrating. Why can't everything just work perfectly all the time?
>:|