I just updated to Firefox 21.0, and as soon as I re-started it I've got this damn Web Console popping up constantly (see attached pic). I've gathered enough info to know I can get to it under the Tools tab and that its listed as Web Developer, but I can't uninstall it at all, or even figure out how to just disable it. I have no need for it & I did not purposely install it...I assume its something new in Firefox 21.0 because I never saw it before the update.

HELP!!

Hmm, try re-installing Firefox.

edit: And you can't uninstall it, it's a part of Firefox for quite some time.

Try press
Control-Shift-K

Try to disable extensions to see if any of then is the troublemaker.

It's been there for a while, but shouldn't pop up by itself. Usually you just turn it off with the cross and it should stay put.

hmm.. can't you just press that "x" button at the end? ;p

CTRL Shift K... or the big X on the right?

That's one ugly looking browser, btw. :p

I tried x-ing out, but it keeps popping up (seemingly whenever it feels like it). Gonna try restarting Firefox.

I re-installed the previous version of Firefox. Seems to work fine now, I guess they'll catch whatever the problem is & fix it at some point.

You could always turn it off through the menu. See attached pic

I switched to Seamonkey and Chrome last year, had too many problems with each new version of Firefox. They should have kept it simple, it used to be the ONLY browser I used.

was ready to leap in to see if i could help, and everyones beat me to it :)
i switch between FF and chrome now depending.

Get rid of Ad-Block, it's known to cause serious memory leaks. I have only Lastpass enabled on my latest install of FF and during a day of use with an average of 10 tabs open at each time it barely reaches 700MB. It usually sits between 500 and 600MB. The only thing I did was to disable plugins by default. So, for example, if a page has flash content in it it requires me to click on it in order to view it. It also allows me to white-list sites.