The site uses Google Custom Search for its site search. It's a service Google offers to webmasters so they don't need to implement their own site search engine.

You can see it faintly in the background of the search box before you click into it (screen shot attached).

Why does that prevent me from accessing any of the tabs? I have talked with Marnie. I am the only person who has told her about this problem. I also used to be able to access all of the tabs. Also, I'm not using the search box on this site. I'm clicking directly on the links. ?????

Sorry, I misunderstood. So for example on the navigation bar there is the word Food which is a link to http://womenspeakers.com/food and when you click that, you end up at Google?

In case one of your extensions is involved, could you test the site in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions, hardware acceleration, and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference?

This might not be relevant, but if you look at your More System Details to the right of your post you'll see one plugin is described just as "plugin" which seems odd. I have a test page which tries to generate a full list of the information available for your plugins. Can you identify that one which is just "plugin" on the list here?

https://jeffersonscher.com/res/jstest.php