Great question.

Your More System Details shows:

browser.privatebrowsing.autostart: True 

That corresponding to a choice in the privacy options:

orange Firefox button (or Tools menu) > Options > Privacy

Either:

• Firefox will: Never remember history
• Firefox will: Use custom settings for history + Always use private browsing mode is checked

Which would mean that all of your windows are set to be in Private mode. Why are all the buttons orange? I think that's a "stealth" feature, but actually I can't recall.

Thank you very much for your prompt and most useful reply. David

_{Note: marked jscher2000's answer as solution}