###Laravel Forge & StarCom Free SSL certificates
Firefox, and probably other browsers, complaint about StartSSL certificates if you don't provide your site's SSL certificate togheter with the StarCom's ones. To fix this, you just have to download those certificates:
http://www.startssl.com/certs/ca.pem
http://www.startssl.com/certs/sub.class1.server.ca.pem
And paste them in the "Certificate" textarea, alongside with your current site certificate. Having all three certificates in the same textarea, save, activate it and you should be good to go.
Forge currently doesn't let you edit a certificate, so I went with the option "Install Existing Certificate", pasted the decrypted key and the above three certificates, saved, activated the new certificate and it just worked.
By the way, you know StartSSL certificates are 100% free, right?