If you can't inspect the certificate via "I Understand the Risks" then try this:

Open the "Add Security Exception" window by pasting this chrome URL in the Firefox location/address bar and check the certificate:

• chrome://pippki/content/exceptionDialog.xul

In the location field of this window type or paste the URL of the website.

• retrieve the certificate via the "Get certificate" button
• click the "View..." button to inspect the certificate in the Certificate Viewer

You can inspect details like the issuer and the certificate chain in the Details tab of the Certificate Viewer. Check who is the issuer of the certificate. If necessary then you can attach a screenshot that shows the certificate viewer.

There is security software like Avast and Kaspersky and BitDefender that intercept secure connections and send their own certificate.

See also:

• http://windows.microsoft.com/en-us/windows-10/turn-off-microsoft-family-settings

See also "Known issues for Firefox users":

• Family Safety update improves web filtering and activity reporting in Windows 8.1 and Windows RT 8.1
  https://support.microsoft.com/en-us/kb/2965142

When you get this for pretty much all secure sites, the problem usually is one of the following:

(1) Error in your system's date, time, or time zone, which throws off certificate validity checks. Sometimes allowing computers to use an internet-based time source can introduce this problem. It sounds as though you already have double-checked this.

(2) Firefox not being set up to work with your security software that intercepts and filters secure connections. Products with this feature include Avast, BitDefender, ESET, and Kaspersky; AVG has a Search Shield feature which can cause this error on search sites. The Premium version of Malwarebytes might also have filtering.

(3) Malware on your system intercepting secure connections.

So... which is it?

If you have any of those specific security products, that would be the first thing to check. We might be able to assist with specific next steps based on what you have if you tell us.

To investigate further, could you inspect the certificate? This is the "I understand the risks" method mentioned by cor-el earlier. In more detail:

Load my test page at: https://jeffersonscher.com/res/jstest.php

You likely will get an error page. Expand the "I understand the risks" section and look for an Add Exception button.

Note: You don't need to complete the process of adding an exception -- I suggest not adding one until we know this isn't a malware issue -- but you can use the dialog to view the information that makes Firefox suspicious.

Click Add Exception, and the certificate exception dialog should open.

Click the View button. If View is not enabled, try the Get Certificate button first.

This should pop up the Certificate Viewer. Look at the "Issued by" section, and on the Details tab, the Certificate Hierarchy. What do you see there? I have attached a screen shot for comparison.

Edit: Clean up copy/paste error.

Here's what I've got.

Time and date settings I set manually without syncing online and the problem persists. I use Webroot anti-virus but it's no longer activated so I have no idea if that would affect it. Malware is possible, as always.

Here are screenshots with the certificate info (Assuming they load)

Thanks to both of you for the effort to help.

Verto Analytics? That's a company which tracks advertising performance and device usage (e.g., http://vertoanalytics.com/verto-device-watch/). I don't understand why its certificate would be used to intercept your browsing unless you suddenly got some new, er, spyware on your system.

Couple things to check:

(1) Proxy Setting

If you check Firefox's connection settings, do you notice anything unusual? Under:

"3-bar" menu button (or Tools menu) > Options > Advanced

Click the Network mini-tab, then the Settings button. The default of "Use system proxy setting" piggybacks on your Windows/IE "LAN" settings, but you also could try "No proxy" to see whether that makes any difference.

(2) Firefox's Safe Mode

This will bypass extensions:

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

(3) Other browsers

If you visit a secure page in Edge, IE, or Chrome and click the padlock and view the certificate, does the mysterious VertoAnalyticsCA show up there?

Maybe you installed this at some point: https://vertosmart.com/

Yeah, my ex who shared this computer did that whole thing. I'm seeing the certificates issued on other browsers for those sites. Well that explains a lot. In safe mode these issues persisted. I had no idea that worked like this.

Well, if they aren't paying you the $5/month, I'd rip it out!

I don't like this whole thing, I called her and had her remove my computer from it. I found it as a trusted root certificate but I don't know how to remove it. You know of any way to do so? That should fix my Firefox problem (I think...)

If the interception software is not running any more, then Firefox should connect directly. If it still can't connect, you might need to shut down/restart Windows, or perhaps there's another piece embedded in the Windows networking settings, for example, a Layered Service Provider or LSP.

There is a procedure to "reset" the Windows networking components, discussed in this thread: After upgrade to window 10, cannot access internet from firefox or chrome. I don't know whether that would help or cause new problems.

To remove a root certificate from Firefox, you can find it in the Certificate Manager, or you could dump the entire Firefox certificate store (cert8.db) and start over with only the certificates that ship with Firefox. This is separate and distinct from removing Windows trusted certificates used by Edge, IE, and Chrome.

To call up Firefox's Certificate Manager:

"3-bar" menu button (or Tools menu) > Options > Advanced

Click the Certificates mini-tab, then the "View Certificates" button. In the Certificate Manger dialog, click the Authorities tab and look for Verto there.

To remove cert8.db completely, see the steps in this article: "This Connection is Untrusted" error message appears - What to do.

Okay, that did it! Thanks for being in with me on the long haul. Sorry it was so complicated.

Thank you for working through it and digging out the certificate. We never would have guessed this one!