Have you received any secure certificate errors yourself? If so, do you use Avast, BitDefender, ESET, or Kaspersky?

If you do, we can give specific suggestions.*

If not, another issues Windows 10 users are reporting is that they were added to a family and their Firefox has become subject to parental controls which causes seemingly random blockages. Try disabling Microsoft Family Safety (or not being part of a family): http://windows.microsoft.com/en-us/windows-10/turn-off-microsoft-family-settings

* For Avast, you can turn off the encrypted scan portion of the Web Shield. I saw these steps in another post:

1. Open the Avast dashboard on the affected system.
2. Select Settings from the left sidebar menu.
3. Switch to Active Protection.
4. Click on Customize next to Web Shield.
5. Uncheck the "Enable HTTPS Scanning" option and click ok.

Thank you @jscher2000, the avast thing seems to have done the trick for me. I don't know why it only happened to Firefox and not to the other browsers, though. But I really appreciate your help. Tnx a lot.

'I need to suddenly give FF permissions for https://mail.google.com/mail/u/0/?uip=0#inbox' to use telephony. How do I do that?

Info: new to me fresh install of W10 on 2009 computer (Why didn't they leave W& be.....argh) Latest FF MS security essentials/Defender/Firewall (all intergrated and not adjustable like before and I can see that using more Anti virus stuff is a can of worms)

Hi wdhc, that is a specific permission the site is requesting? Do you have the Google Hangouts add-on(s) installed?

Hangouts is installed. But, not even in Chrome can I make or receive a call. I just get the screen to install it again. Done that about 30 times now, each time making a change such as making a Firewall exception for the .exe,, a Flash exception, making my location visible, making sure all is in English, not my native language.... No dice,

It is probably not a FF issue, but a failing to install or run programs in W 10

Only one of my 5 recording/editing business programs installed at all. And that 1 took several tries and a lot of tweaking. According to the support boards I am not the only one who is looking for a W 7 disk. This W10 conversion was forced upon me with the hard drive repair to my despair, after I bought a every expensive new computer to replace this 2009 workhorse. But the new one was so slow and unstable, I never even got this far basic set up before it had a fatal crash that hurled it back to factory settings, so I returned it, as there was no way it could ever run my programs! I really don't need all this waste of time at my busiest time of the year!

Thank you, and let me know if there are angles I missed as I am at all not a programmer!