A warning is displayed in the Chrome console window regarding your certificate
This error usually occurs because the website content contains both secure and insecure content.
This error can be returned by Firefox browser when your server presents a weak Diffie-Hellman key exchange.
Ensure you have installed the Intermediate CA correctly on your server.
Error produced by Firefox when visiting website secured by a no longer trusted certificate.
This error indicates the certificate for the site has been revoked. If you are the site owner you can contact the certificate issuer for further information as to why this might be.
Information regarding the upcoming distrust of Symantec, Geotrust, Thawte and RapidSSL HTTPS certificates