Check the date / time on your computer.

kindly clear this probable of get certificate

anand847
Please do not use existing threads to ask a question, but start a new thread instead.
Then you also can provide troubleshooting information like your operating system and installed plugins (about:plugins), and extensions (Tools > Add-ons) and we will be better able to help you.

While I can't say for sure this is the solution to what I've been experiencing as described in this post, I'd say it is highly likely that the problem will not re-occur as indeed my computer's date and time was not properly set.

Ya know what? I guess Mozilla considers itself untrusted. Because guess, just guess, what screen I got when I tried to log in! You guessed it! "This page is untrusted." This is rediculous! My computer was fine and I never had this problem until I decided to disconnect my computer last week to repaint my room. Then when I hooked everything back up, all the sites I used to visit WITH NO PROBLEMS , now Firefox has an issue with. Telling my they're all untrusted. This is making me crazy. I corrected the date and time, restarted. Now they're saying I have to mess around with all these certificates? I just want to disable what they're blocking. The only reason they're certificates in there is because of when I've visited sites and was able to at least browse by clicking to get these damn certificates. I STILL can't pay my capital one card!

Some firewalls monitor secure (https) connections and send their own certificate instead of the website's certificate.

• Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button to inspect the certificate and check who is the issuer.

Only leave the mark in the box at the bottom to "Permanently store this exception" if you trust that certificate.

• Click "Confirm Security Exception" to enter the site if you still want to go to that website.

If the issuer is your security software then you either have to disable that check in your firewall or install the root certificate of that firewall. See Configure firewalls so that Firefox can access the Internet

Even when I permanently confirm the security exception, Firefox does not recognize the same site the next time, or the time after that, or the time after that--each time permanently confirming security exception.

I want to know what setting to make to disable this altogether.

Happened to me, too.

If the date and time on your computer are correct then another possible cause is security software (firewall).

Some firewalls monitor secure connections and send their own certificate instead of the certificate from the web server.
You can check that if you click through the steps and get the certificate and look at the issuer.
In such cases you need to install the root certificate of that firewall to make Firefox recognize the issuer of the certificate or disable monitoring secure connections (port 443).

See also http://kb.mozillazine.org/Firewalls and Configure firewalls so that Firefox can access the Internet

THANK YOU!!!!!!!!!! As soon as I checked that I saw I was on the wrong year and didn't notice and have no idea why my PC did that but it fixed this problem immediately, thank you so much!