Recently I have a big issue with Firefox. I can get to some pages like CNN.com, Facebook.com, Yahoo.com but try and go to MLB.com or NFL.com and it will not load due to a connection is not secure. I have uninstalled Firefox, removed the cert8.db file for the user profile and even used the command %appdata%mozilla and removed the Firefox folder. After a reinstall the problem is still there. The sites in question load fine in IE, Edge and Chrome just not in Firefox. I use Firefox occasionally for a few add-ons that are not available in the other browsers. Any suggestions?
I do run ZoneAlarm firewall and Malwarebytes and have for years. This problem is new.