It is my understanding all sites are not Firefox friendly (which is unfortunate).
I maintain IE and Firefox for just such situations.
You might call your bank and ask them if they can help.
Using Firefox and XP home, I've had a problem logging on to my bank. I can get the home page fine, and then the log-on page but after that the browser just drops out. A window from Mozilla Quality Feedback Agent advises that I'm in a queue to send a program crash report and then I get a message that the agent is unable to connect to the server and to check my proxy settings. How do I do this - and what exactly should I do?