I've been using this for a few years now and it's always worked well, but I think the Firefox 1.6 release is messing with it. It seems to be randomly forgetting sites where I've allowed comments. On some sites, comments are hidden and the balloon icon is greyed out, so I have to reload the site a couple of times until the icon turns black so that I can click it and enable comments. It was working fine before the FF update.