I hope this is fixed. Just because Firefox is on crazy version numbers - they'll be on v20 soon - doesn't mean the browser is very old. Many of us hold back due to bugs like not being able to close by double clicking top left in Firefox, or due to addons not working. Not one of my addons works with v6!
just update Firefox to the latest version...simples! I'm on Firefox 7.0, and no issues!
I do however realize the pain, that by updating your FF browser, some 'Paid' add-ons such as RoboForm, may fail to work, and that may cost you, but for this OP issue, it solves it!