No connection to any sites in Firefox

samuria said:

Check your date and time

Agree!
For starters, pleas make sure your system date and time are correct.
If they are not, fix them and consider replacing your CMOS battery, which may be dying.

(Also: is this the same computer as the one here and here???)

MM

CMOS battery is a mother board battery about the size of a nickel

Hi:

EDIT: Thanks, @ThrashZone -- you beat me to it, while I was typing.

Actually, even desktop computers have a little battery inside the case on the motherboard.

CMOS battery

When it starts to die, the computer's time/date will drift.
That can be one cause of the error you report.
It happened to another user recently HERE.
When the user replaced the battery, the browser error went away.
One hint that the CMOS battery needs to be replaced would be that system time drifts off again, after you fix it.

As for changing your DNS servers, the other suggestion @samuria made, I'm not sure that will fix your issue. I will defer to @samuria to walk you through that.

Until then, I suggest perhaps trying the steps suggested here:

https://support.mozilla.org/en-US/kb...UNKNOWN_ISSUER

If that does not work, we may need to collect additional basic system diagnostic information, in order to better assist you.

Thanks,
MM

I'd personally use Google's DNS instead of OpenDNS. Some people have reported odd redirects with OpenDNS.

IoNGeNeRaL said:

I'd personally use Google's DNS instead of OpenDNS. Some people have reported odd redirects with OpenDNS.

Agree -- Google DNS is probably a better choice.

But I wonder if perhaps there isn't something else going on with the OP's system.

Might be worth a bit more investigation, or at least the troubleshooting suggested in the Mozilla support link I just posted.

Cheers,
MM

Question: What is your Antivirus? Some are known to use their own certificates for SSL scanning and could possibly cause that error.

Second question: Your screenshot

shows a secure connection to sevenforums (https) but sevenforums only uses http. So obviously the connection won't work.

Suggest: Launch Firefox and type about:support in the address bar then press [B]Enter[B]

In the window that opens choose "Copy text to clipboard" and paste the results here.