Try the Firefox Safe Mode to see how it works there. The Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open the Firefox 4.0+ Safe Mode by holding the Shift key when you use the Firefox desktop or Start menu shortcut.
• Or use the Help menu item and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Don't select anything right now, just use "'Start in Safe Mode" To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shift key) to open it again. If it is good in the Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one.

Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

Do you remember which file (chrome:// URI) was causing the message?

Evidently several addons were throwing the error, including NoScript, Tab Utilities, BetterPrivacy, Ghostery and RSS Ticker. These are "must have" addons for me, so disabling them is not an option.

I had previously researched all the possible solutions to this problem and found that none worked. Frankly I have tired of troubleshooting and have now resorted to reverting to the "Last Known Good Configuration" and will stick with it until such time that I have no option but to upgrade Firefox to a subsequent version. It ain't broke now, so I ain't gonna fix it. Cheers.

You can still try to check out is one of those extensions is causing your issue.
Then you can contact the developer for advice or see if there is a development version of the extension available that fixes it.