Most of the times after the release of a new Firefox version, add-ons may become incompatible. It's up to the developer to address these issues and update it accordingly. You can contact the developer from their add-ons page.

Zone Alarm isn't an "Add-On" to Firefox - I've been using it since the mid-1990's. The days of a 286 clone, dial-up, and DOS 3.5 for work-groups. It was the first firewall to control both outgoing as well as incoming data. (The current crop of 'nanny' programs; automatic updates, or run automatically at a fixed time each week, "I can run your machine better than you can", seem to create more problems than they solve.)

Firefox does not disable the separate applications like Firewalls and virus scanners. Yes we know that the Zone Alarm itself is not a Extension for Firefox.

The message was stating the Zone Alarm related Extension you had at time was not compatible with that version of Firefox you had at time. The separate Zone Alarm should have still been fine.

It is also not the job of the Firefox browser to be made compatible with the thousand of Extensions out there, but the other way.

Thanks for the explanation - and I must admit, somewhat more polite than my post. I don't want to have to again go through the trauma of having to keep my firewall/anti-virus program working properly, I guess I'm stuck with Chrome.

Your Firewall and AV should still work fine as they do not need to have extension integration to work properly.