Having the same problem in EVERY window opening. It's crazy! Mozilla needs to get this problem solved and quickly. It's annoying.

I have it too. It started 11/11/2012 on 2 dell computers, in different locations and using totally different network systems.

I have been getting this message as well. It has been frequent since updating to FF 16.0.2 which I am running on Mac OS X 10.6.8, but I believe it was occurring before this update. I have been getting similar error messages involving Javascript and XML attributes in previous versions. Is this a bug that will be fixed in subsequent versions of FF and/or Javascript?

I just started getting this error message, too, each time I open Mozilla. Very annoying. Any ideas on how to fix this issue?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Thank you kindly for responding, however, it is far too technical for me. I emptied. Guess I just have to live with it.

I cured it by disabling the extension GoodApp 2.0. That's the GoodSearch toolbar. The hardware acceleration can remain on without giving the error message.

I have been using the Good App because it allows me to search and raise money for a non profit of my choice. Why would the error message show all of a sudden? I have been using the Good App for about 2 years and this is the first error message. Should I disable the Good App then reinstall? How do I do that?

To dcgoodson: Many thanks for your helpful solution! The message had been annoying, and your suggestion worked like a charm!

To remove the goodsearch application:

1. go to "tools", then "add-ons" then "extensions".

            (**Depending on the theme you use, you 
                 might have to click on the orange Firefox
                 button in the top left corner to find 
                 "tools"**)

2. click "remove" to the right of GoodApp 2.0

Then go to goodsearch.com. At the bottom of the page, click on "goodapp" and install GoodAp 2.1. That one doesn't give the annoying message.

Thank you! This solution worked after two days of aggravation and trying to solve the problem other ways!