So, I did an obligatory virus/malware scan, which I've been doing since my previous virus scare. And low and behold, I find a trojan. Not much of a trojan, mind you, and it was taken out swiftly and with ease, but a trojan nonetheless. So I suppose my question is how is this possible? I'm running Firefox 3 with its built-in fishing and malware dealies, running the ad-block and flashblock extensions, 3rd party cookies turned off, and not frequenting sites of ill-repute. I'm also running Spybot: Search & Destroy and Spyware Blaster to block negative cookies and websites/etc. Plus ZoneAlarm for the inbound/outbound access (with nothing allowed that shouldn't be). I have Avast running on full protection, it's literally deep-scanning every file I touch on a second by second basis. While SpywareGuard, BoClean, and TeaTimer run by its side (and they're fully compatible when running together). All of them have been fully updated. And I haven't been downloading many files outside of safe program updates. How could it slip through those defenses? And/or what else could I be doing?