"Add Exception" button no longer visible on "untrusted connection" page
When using the 64bit version of Firefox 4 on Fedora 12, self-signed certificates which I have previously added exceptions for are no longer trusted, and the "I understand the risks" link and the "Add Exception" button no longer appear on the "Untrusted Connection" page, as can be seen in this screenshot:
http://dl.dropbox.com/u/368707/ff4-ssl-error.png
If I go to the "Advanced" tab of the Preferences window, click the "Encryption" tab and then click "View Certificates", I can add see the self-signed certificates I previously added exceptions for. If I click the "Add Exception" button on this dialog and try to add the exception again, the certificate is still not trusted.
I deleted my old profile and tried again with a new one, and the problem still reoccurred.