First, just a note that JavaScript is the scripting language used by most web sites and built in to Firefox. Java is a different programming language that runs using a plugin from Oracle (previously Sun). It was a bad idea to have such similar names, but that mistake was made long ago... Anyway, do you use NoScript or any other security add-ons that relate to scripting? In the case of NoScript, your bank may be using a different domain for part of the process. If not, I wonder whether the bank's site doesn't fully support Firefox. Do they list any system requirements? Finally, your Firefox is pretty old. You may want to update to 3.6.17 to get the security patches introduced in the past 9 releases.