Hi Patio! Always good to be able to chat with you.
I'm running Mint 17.3, freshly scanned with ClamAV. That screenshot I attached to my orig post shows a message that I have never seen before in 10 years of using Firefox. Now, I have seen another warning message (many times) that warns the website's Certificate has errors - "this connection is untrusted" & it asks if you want to continue or "get me out of here".
Hope this sheds some light on the issue.