The current version of Firefox is 20.0.1. You should be able to confirm your version using

Help > About Firefox

Where are you seeing pop-ups about version 4?

By the way, updates are available for Adobe Reader (you can check from inside Adobe Reader, Help > Check for updates) and Flash (you can get from http://get.adobe.com/flashplayer/).

They popup when Firefox does an update, urging me to try version 4, so I'm confused which version is the latest.

Version 4 is ancient now. 20.0.1 is current.

Is it something popping up from a particular web page? If so, what is the URL of the page?

Could it be originating from an old toolbar? Those usually show up here:

orange Firefox button (or Tools menu) > Add-ons > Extensions category

It's possible one of them is responsible for this strange pop-up, but if you have a lot of extensions, and unless this dialog comes up all the time, it might be easier to ignore the message than to track down the issue.

It comes on a wakeup, and the message includes a pitch for Firefox for Android. On your advice, I'll just ignore it since I'm at v20 and it works just fine. I'll do a screen grab next time I see it. Thanks,