Ok I don't know why yours was buggy. I've just downloaded and set up FF3.0.19 with the ColorZilla, Web Developer, MeasureIt, HTML Validator, Java quick Starter, Microsoft .NET Framework and Personas plug-ins and the reply form is working just like it should. I suspect the problem was due to one of your old add-ons.
And you didn't just miss one version. You missed 3.5 as well.
They stopped development on the 3.0 series sometime last century.
ETA: I posted this on 3.0.19.
Devious, treacherous, murderous, neanderthal, sub-human of the West.