SSL is disabled
From MozillaZine Knowledge Base
SSL (Secure Sockets Layer) is a security protocol that secures communication over the Internet. Most banking sites and online stores require sensitive information be sent over SSL. This article deals with an "SSL protocol has been disabled" error. For information on other messages received when accessing secure sites, see Error loading secure sites.
If SSL is disabled, you will see a dialog box or error page, with a message similar to the following:
Note: you can't make a permanent exception in Firefox 3.5 or newer if Firefox is in Private Browsing mode.
If you see one of these errors, try the following solutions:
Check SSL settings
Check that SSL is enabled.
Check proxy settings
If you're using a manual proxy, make sure "Use this proxy for all protocols" and "SSL proxy" in "Tools -> Options -> Advanced -> Network / Connection -> Settings" (Firefox 2 and above) or "Edit -> Preferences -> Advanced -> Proxies" (Mozilla Suite/SeaMonkey) are set to the correct values.
Mozilla applications require a loopback connection to be available for SSL. Check your firewall settings to make sure you have not blocked incoming connections to Mozilla applications. See the Firewalls article for details on firewall configuration.
Check date and time
If you get an error about an expired certificate that should be valid according to the date or a certificate that will be valid in the future then check the date and time on your computer to make sure that both are correct.
You may simply have an out of date version of the page in your cache. Try clearing the cache.
You can try this SSL test. If your browser passes, it's likely a problem with the site you're trying to connect to.
SSL disabled on Windows 9x systems after upgrade
If you're on Windows 98 or ME and SSL no longer works after updating to Firefox 188.8.131.52 or later, Firefox 184.108.40.206 or later 1.5 builds, and Thunderbird 220.127.116.11 and later 1.5 builds, you may be able to fix it by installing IE 6.0 SP1.
If, rather that downloading the program from Mozilla, you compiled the Mozilla application yourself or received it from an administrator, it's possible SSL support was disabled.