Who is in your network?

The certificate for websites is valid only for a specific time. Suppose a website shows a certificate with validity dates that never match the dates of your computer clock; Firefox can’t examine its security and offers you an error message.
Such errors can be fixed by setting the valid date, time and time zone on your system. Suppose the problem is not resolved or can be caused with some other reasons like misconfigured web server or an expired certificate. In that case, you must call the Mozilla Firefox Customer Service Number to resolve it immediately.