505 means "HTTP Version Not Supported" (for example, if you were using HTTP 1.1 but the site could only accept HTTP 1.0). I'm sure Firefox isn't using a different version of HTTP than everyone else, so my guess is that what they *mean* by that, is that your *browser* version is not supported. One of the headers sent with every request is called User-Agent and it tells the site, "Hey, this request is coming from Firefox 7". You can use https://addons.mozilla.org/en-US/firefox/addon/user-agent-switcher/ to send a request that says you're on Firefox 6, even though you're actually not.

If this does fix the problem, you should also tell your bank that they should either not do User-Agent sniffing at all, or if they must, make sure they're always supporting the latest version. Otherwise, they're encouraging people to stay with unsupported and potentially unsafe browsers.

Thanks for your info ,being a newbie, not to sure how to use the user-agent- switcher. Another site has come up with an error message -runtime error!

Thanks