Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

followed instructions but didn't see "start in safe mode" when my yahoo home page came up. should I being doing this w/o my home page? how do I get to "basic" firefox page?

Did you hold down the <Shift> key before starting Firefox?

I had not but I just did and f-fox [and home page] came up in safe mode BUT I still have the problem....e.g, I can get into my yahoo email account but it's an entirely different "picture" without some convenient functions.

I've been using firefox for years and never have had a problem [using W10, BTW] but this has been driving me crazy so I'm starting to "export/import" favorites, etc to IE11.

I called for more help.

Fred...

I went to Program Files and found "javasetup8u111" but it had several executables and ".dll."

When I tried to get to my wife's email via google, I got this: "it seems JavaScript is either disabled or not supported by your browser"

To this IT-challenged senior, it would appear that Java is installed but not "executed"....???????? Is there some file I need to "execute'???????

I called for more help.

Make sure your Java (Not JavaScript) is up to date Verify Java and Find Out-of-Date Versions {web link}

Version 8 Update 111 Release date October 18, 2016 http://java.com/en/download/manual.jsp