You do not say what site. You do not say kind of popup or give detail. You have send data to Mozilla turned off so that on not saying what extensions you are using and a/v solutions as well as any information that would be helpful to solving this. None.

Windows 7 I think..............is all I got.....

Here is the popup/web address

That's not a pop-up - that's a dropdown that you get when you click on the Page Info button.

Does that appear without you clicking the button (the little 'i' in a circle)  ?

Yes it does. I basically start the program in the same way the 'run' command does: Enter in run - C:\Program Files (x86)\Mozilla Firefox\firefox.exe https://www.crediblebh.com/secure/login.asp

The drop down displays automatically when the browser opens.