Do you often use this Web Clipper add on? Perhaps you should just disable it. You can find instructions on how to do that here

Sorry, I should have said that it's already disabled. I didn't do this, but in the Add Ons manager it says it's incompatible with FF 13 and appears to have been disabled automatically.

I did try to remove it, but if I click away and then back to the extensions tab, it still appears there, though it remains disabled.

If that add on is already disabled, should I assume it's NOT the cause of this issue? If so, I'm not sure why Web Clipper appears in the error messages I'm getting.

I've attached screen shots of 3 of the 24 error messages I get, in case that helps.

Looks like their code is really messing up Firefox. Have you tried removing the Add on entirely?

If it still happens, check out this link: http://discussion.evernote.com/topic/27004-evernote-web-clipper-isnt-working-with-firefox-13/

Thanks for all your help so far, and I'm sorry to be a problem child but...

I don't use Web Clipper much it so I'd be happy to remove it, but I can't. It's disabled, but if I click the remove button, then click off the extensions tab and come back, it's back, ie it did not remove. I don't know if there's another way to remove it?

I'd also be happy to install the Web Clipper update, as the Evernote folks have told me to do, but I can't do that because Firefox tells me it can't find the needed file when I try to install the update.

So I'm stuck in limbo, not able to remove the Web Clipper add on, but not able to update it either.

Meanwhile, I get those 2 dozen javascript errors popping up every time I click on a link in Firefox that opens a new tab or window.

It's like a bad dream, spinning my wheels and can't get anywhere. It's far from serious of course, but really annoying.

Any more ideas?

The only other Idea I can offer up for you is to uninstall Firefox and start with a fresh install. I know that's a huge inconvenience too, but it sounds like that old version of their add on has really messed up the program itself.

If you're feeling up to it you could always create a new Profile to use and make it your default: creating a new profile

Profiles are basically like user accounts for firefox, so creating a new one is like having a clean installation (though not really) and it will also not have any user data ( like passwords history, favourites, etc.) You may be able to migrate that data into it though: Recovering important data from an old profile

Forgot to mention: Those method might require some work using a command prompt, but as far as I can tell all the steps are documented. Good luck!

Thanks so much for you patience and continued help. I saved my profile as per the instructions, did a clean re-install, and copied my profile over. All seems to be working fine now, with no more annoying pop up error messages. Much appreciated!

Awesome! Glad to hear everythings back to normal!