In my Firebird 0.7 (Win XP, TBE) the websearch by right-click-menu doesn't work. I've had the same problem with Mozilla 1.4, but I mean it worked with FB 0.6.1.
try deleting pluginreg.dat and registry.dat (don't worry, they will be regenerated at startup) from your Phoenix directory (the one containing your profile).
Mozilla Firefox 0.9 20040817
Windows XP Professional SP1
mozillaZine is an independent Mozilla community and advocacy site. We're not affiliated or endorsed by the Mozilla Corporation but we love them just the same.