It's always suggested that more then one virus scanner be used, for the very reason you pointed out. If I suggest scanners I recommend a range of them, usually AVG/Trendmicro/SwatIT/TheCleaner. Personally, I have Norton AntiVirus and AVG both running in the background, but never have them both scanning. This is because I scanned with NAV and it found nothing, then I scanned with AVG and I had some sort of trojan (this was quite awhile ago, since then I've remained virus-free!)
Thanks for that other resource
*tries to remember it for the future!*
Happy chatting!
Regards,
