Javascript doesn't get disabled, in fact we continually are adding more features to Firefox's javascript support. Are you maybe meaning Java, which is a totally different third-party plugin?

http://kb.mozillazine.org/JavaScript_is_not_Java

Perhaps you have some extensions that deal with JavaScript like NoScript.

Are there particular sites that you notice reporting this problem? Sometimes you get a false message about JavaScript when the real problem is that a plugin is disabled. But that's just a guess as to one possible reason.

I don't use NoScript, and no, I'm not confusing Java with JavaScript. (I know Java a lot better than I know JavaScript.)

The toggle (javascript.enabled) in about:config was turned to false.

I've had to download the full version of Firefox from the website on the last two upgrade cycles because the install on my iMac says it thinks it's being tricked into downloading a potentially malicious version.

Both times, the install toggled JS off. All other preferences, including open tabs, were kept.

Is this mistrust issue the root cause?

Did I not get a proper certificate update or something?

I have a coworker who told me he has the same issue.

By the way, I apologize for my original tone.

I had just upgraded Firefox, then got on a WebEx to try to demo some code fixes, only to find that JavaScript had been toggled off.

I probably shouldn't have upgraded before a demo anyway.

My apologies.