Hmm...... I've been using Avast successfully since having to scrap AVG because after a certain update it started to cause my fully updated winXP Pro to crash towards the end of the boot-up process.
My computer stays on for about 13 hours a day and I've never noticed Avast updating itself except to note that it always appears to be fully updated when I check. It has found the odd virus - usually in my explorer temp file and has inserted itself nicely into Outlook (not express) preventing me even from seeing any text in the one or two infected e-mails I receive every day.
I have certainly never heard of Skyfalcon before, but if it is anything to do with Avast, maybe my copy of AdWatch which you can get as an addon to Adaware has kept it out. I see it's icon on my toolbar glowing red from time to time.
P.P.