Javascript failing in Firefox/Firebug?

I'm using Firebug to develop a JS app. All of a sudden, when I got to the page, it appears that I开发者_JAVA技巧 do not have JS enabled - the <noscript> warnings are rendered, and nothing works. When I go to the same page in Chrome, everything works fine.

What could be happening? I reverted recent changes back to a point where it worked, but it's still failing.

UPDATE: I just went back to the page in question, and now it works fine. I had been working on it in Chrome. Odd.

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Honestly, I've had to disable Firebug entirely. Way too many errors and bung-eyes there.

Worked wonders for a long time, but recently... not so.

I've switched to Chrome + Developer extension - which does fall short, but it does the trick.