In posts #29 and #32 I stated that this was with just the browser and WebRep. In one case, it was a completely fresh install of FF4.0 (with no prior installation of FF before) and the other, it was on my system with all add-ons disabled except WebRep. In both cases, WebRep failed in the manner I've been describing.
I do appreciate the interest, but I have now uninstalled WebRep (at the Avast! control panel). When it worked, it was nice to see how the site/page fared by 'votes', but when it stopped working it didn't really matter. I was just curious as to why it stopped working (for me, apparently, and nobody else).