Since many people here are using OA and Antivir Premium same time. I thought to be informative and mention that the default settings of OA will let port 44080 (WebGuard uses it) to be totally open (for example grc.com reports its status as open). To get stealth status you have to restrict port 44080 (and 44110 if using MailGuard). I tested functionality of WebGuard at one known site (if a threat at all) and it worked normally reporting about a threat and then denying access. All others firewalls, what I have tried, filter it default (PC Tools, Comodo, Sygate, Windows XP Firewall and Outpost). Is it vulnerability? It has been there since I started using OA Free (version 2).