Two things:

(1) It looks like Firefox is blocking some content in that through the Tracking Protection feature (shield icon on the left end of the address bar). Please see this article for more information on this feature and how to make an exception: What happened to Tracking Protection?.

(2) It's a little hard to read, but it seems to say "We've detected that you're using an older version of Internet Explorer". This is not a normal message to receive when visiting a site in Firefox 45. Do you use any add-ons that modify how Firefox might identify itself to websites -- this influences what code sites send to the browser.

One site for testing might be my test page, which displays how your browser identified itself in red: https://www.jeffersonscher.com/res/jstest.php

followed steps nothing resolved,using windows 10 with current version of firefox deleted and reinstalled still have overlay only on start page

It's your home page? Does the mess clear if you use Ctrl+Shift+r to reload bypassing the cache?

Actually in automatic private browsing, nothing should need to be cleared at startup, so it would be strange if that helped. However, I think it's worth a try.

When you visit my test page in Firefox, what user agent string is displayed?

tried your suggestions nothing worked

Third time asking: When you visit https://www.jeffersonscher.com/res/jstest.php in Firefox, what user agent string is displayed?

both browser and navigator.user agent show in red Mozilla/5.0 {Windows NT 10.0; Win64; x64} AppleWebKit/537.36 {KHTML, Like Gecko} Chrome/46.0.2486.0 Safari/537.36 Edge/13.10586

cmbretiree123195 said

both browser and navigator.user agent show in red Mozilla/5.0 {Windows NT 10.0; Win64; x64} AppleWebKit/537.36 {KHTML, Like Gecko} Chrome/46.0.2486.0 Safari/537.36 Edge/13.10586

That's the identification for the Edge browser. Is that what you see when you visit the page using Firefox?