I guess you are updating from here : Open Help Menu -> About Firefox . Try once for resetting firox,it will solve many of problems see here how to do : Reset Firefox

If problem persist then You can try a fresh installation from here: Mozilla Firefox .

Also tried a fresh install after deleting. Problem is still there after the fresh install. No change. Running on MBPro OSX 10.9.3 and Safari 7.0.4

What is the link of the update message? We already saw some users receiving these messages from a fake update page.

1. Start Firefox in safe mode to check if one of the extensions is causing the problem:
   • Firefox in safe mode
   • See Troubleshooting extensions and themes if the problem doesnt occur in safe mode.
2. Malwares can also cause these problems:
   • Problems with malwares
3. You can also use some add-ons to block ads/popups:
   • Adblock Plus
   • Simple Adblock
   • Adblock Plus Pop-up Addon

What is your Homepage in Firefox as this sounds like the old Firefox start page by Google as it has the message of "You're not on the latest version of Firefox. Upgrade today to get the best of the Web!" below the search box.

http://www.google.com/firefox

Google has not maintained this start page ever since Firefox 4.0 was released as it has been about:home since.

James

thank you big time!!!!!! You solved it. Much appreciate it.

Doug

Note that if you prefer a Google search page with a Firefox logo then you can use http://start.mozilla.org/ that only shows an outdated message if you use Firefox 3.6 or lower.