Thanks again for everyone.
That webpage now opens sucessfully, albeit with a few seconds struggle, after I have uninstalled the "Videodownload helper" extension.
@Hero999,
Yes, FF3 is a bit annoying, especially it does not highlight a "https://" address in yellow which I have grown used to. I have to install an extension to get this feature back.
Another annoyance is it does not allow me to open a link in a tab as default but replaces the existing webpage window instead. I was told I can "middle" click or press "Contrl" key while clicking to get that but I do not use a three button mouse.