Sounds like a context menu, which you normally would call up with a right-click or Ctrl+click. If you try those methods, does it match what you're seeing or is it something different?

It might help if you could capture and post a screen shot of the navigation window. This article has tips on that: How do I create a screenshot of my problem? Please cut out or blur out any sensitive information in the image before attaching it to a reply.

Update your Flash Player Version 18.0.0.160
https://www.adobe.com/products/flashplayer/distribution3.html

See if there are updates for your graphics drivers https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

here is the screener of the popup i get all the time.

it IS the context menu you speak of cept i do not call it up, it just pops up?

Do you mean the small window; Save Page As ?

That is the right click options window. Press the <Esc> key.

Firefox might be having issues with your mouse or keyboard. Have you noticed any other strange behaviors?

On Windows, this kind of phantom keyboard/click behavior can be caused by low batteries in a wireless input device, radio interference, or sometimes a glitch in memory that isn't corrected until the system is shut down and started up again.