Sorry you're having this problem. I'd recommend uninstalling Firefox and then re-installing it. Here's the article for uninstalling Firefox.

Uninstall Firefox from your computer

Here are the links to install Firefox 3.6 or 11.

Firefox 3.6 http://www.mozilla.org/en-US/firefox/all-older.html

Firefox 11 http://www.mozilla.org/en-US/firefox/all.html

Thanks for the reply. I had already tried that. I uninstalled Firefox by dragging the ap to the trash and then downloaded a new version and dragged it to Applications. Once I start Firefox, it seems to operate satisfactorily, but the error messages come up on console many times a second.

You downloaded Firefox for Mac right? If you've downloaded it for Windows or Linux, then that's probably why.

Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

• https://support.mozilla.org/kb/Basic+Troubleshooting#w_8-make-a-new-profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox