You'll need to enable SSL renegotiation, do this by pointing your browser to about:config. After confirming that you know what you are doing, you need to start typing in:
security.ssl.allow_unrestricted_renego_everywhere__temporarily_available_pref
set it to true (by double clicking it). After this you should be able to access the site.
Do you want to use Thunderbird to check your AKO email and digitally sign? Here's how
Public key enabling Firefox information

