Hello Angela.

It's possible that you are having a problem with some Firefox add-on that is hindering your Firefox's normal behavior. Have you tried disabling all add-ons (just to check), to see if Firefox goes back to normal?

Whenever you have a problem with Firefox, whatever it is, you should make sure it's not caused by one (or more than one) of your installed add-ons, be it an extension, a theme or a plugin. To do that easily and cleanly, run Firefox in safe mode (don't forget to select Disable all add-ons when you start safe mode). If the problem disappears, you know it's from an add-on. Disable them all in normal mode, and enable them one at a time until you find the source of the problem. See this article for information about troubleshooting extensions and theme and this one for plugins.

If you need support for one of your add-ons, you'll have to contact its author.

You have or had an extension installed (MegaUpload toolbar) that has changed the user agent from Firefox/3.6.6 to Firefox/2.0.0.11.

You can see the Firefox version at the top and the user agent at bottom of the "Help > About" window (Mac: Firefox > About Mozilla Firefox). You check (compare) what websites see: http://whatsmyuseragent.com/ - Whats My User Agent?

You can check the general.useragent prefs on the about:config page. You can open the about:config page via the location bar, just like you open a website. Filter: general.useragent If general.useragent prefs are bold (user set) then you can right-click that pref and choose Reset.

See also http://kb.mozillazine.org/about:config

Hello, I was having the same problem with that irritating EM.add update listener popping up every time I opened mozilla firefox. I went to the top of page and clicked on to tools, then clicked on add- ons and disabled all the add-ons and it took the problem away. pretty easy.