Is it happening only with Firefox and with no other browser ? Did you recently upgrade it or reinstalled it ? This is a specific error that should ideally be not coming if things are proper

It appears that Firefox is not properly installed (when you run it, it goes to a point and after that due to some issue it throws that error message. Also see Note below). May be you can download again and reinstall it ...

Note: XUL (XML User-interface Language) is a cross platform language for describing user interfaces of applications. XUL (pronounced zool) was created to make development of the Mozilla browser easier and faster.

Yes, it only happens with Firefox...recently installed/upgraded to firefox 9.01. I will download again and reinstall. thanks.

Any luck with the new installation ?

No...I am getting the same error message. Help!

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

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

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

After I started in safe mode and reset the toolbars, it got fixed! I am not getting the error message anymore. Thanks much.

I have re-installed Firefox so many times because of different issues it's not even funny. This Type Error message doesn't go away. Also, sometimes my Google Calendar doesn't work, and sometimes it does. What's up with that? I have Windows Vista, and I'm wondering if that's part of the problem? Please advise because Google nor Firefox has any customer service numbers to be able to reach them. Thanks! Have a nice week, ya'all! Later, godis1224

Did you try to disable all extensions to see if that helps?

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