SCN: (auto) login no longer working with latest Firefox

When accessing SCN using the latest Firefox 27.0.1, the (auto) login no longer seems to work. When I try to login manually using the "login" link, the popup for my username and password does not appear. I can see that there is some SAML stuff being done, but this does not result in a successfull login but in a SSL_ERROR_HANDSHARE_FAILURE_ALERT. This is not the case when I remove my SAP Passport certificate from Firefox (which is something I don't like to do since that would mean I cannot SSO into the SMP anymore). Has anybody else observed this behavior?