Mozilla says
secure.freerepublic.com uses an invalid security certificate.
The certificate is not trusted because it was signed using a signature algorithm that was disabled because that algorithm is not secure.
Error code: SEC_ERROR_CERT_SIGNATURE_ALGORITHM_DISABLED
Likely because SSL (the before versions of the “S” in https:) is still being used instead of the newer/mandatory TLS style of website protection for doing commerce online.