Please update to Firefox 17.0.1, then test again.

You get that problem if you select the Firefox program to handle a file if you get an "open with" dialog.

• https://support.mozilla.org/kb/Firefox+keeps+opening+many+tabs+or+windows

I updated to 17.0.1 and now the problem is worse than before!! When I click on an email address, and Firefox begins opening tabs VERY rapidly, I have to click end task in Task Manager, same as it before the upgrade. Before I upgraded, that was the end of it. Now, immediately after closing Firefox, it reopens by itself and continues opening tabs as fast as it can. Over and over again. Nothing I can do will stop Firefox from opening again, and opening tabs quickly. I had to unplug my computer to get it to stop.

Reset Firefox. Refresh Firefox - reset add-ons and settings

Did you delete the delete the mimeTypes.rdf file in the Firefox Profile Folder to reset all file actions?

• http://kb.mozillazine.org/mimeTypes.rdf
• http://kb.mozillazine.org/File_types_and_download_actions#Resetting_download_actions

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder

Cor-el, your suggestion to delete the mimetypes.rdf file solved my problem! Thank you very much!! I don't know if these questions are ever "closed" or labeled as "resolved" but if so, you may mark this one resolved! Thank you so much!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

You're welcome

I have the same problem on a Mac OS 10.8.3 and Firefox 21.0 (the latest version).

I followed your directions but it doesn't fix the problem. Is there a fix for the Mac?

Thanks!

MimeTypes.rdf does not exist on my computer

browser.download.pluginOverrideTypes does not exist on my computer

plugin.disable_full_page_plugin_for_types does not exist on my computer

Resetting Firefox does not work either.

In Mac OS X v10.7 and later, the $HOME/Library folder is a hidden folder.

Open Finder and use one of these:

• Go > Go To Folder (Shift-Command-G) and in the dialog type: ~/Library
• Open the "Go" menu and hold down the Option key to make the Library appear

• http://kb2.adobe.com/cps/909/cpsid_90947.html Access hidden user library files

Which files are in the Firefox profile folder?
The mimeTypes.rdf files should be one of them.

Did you use the button on the Help > Troubleshooting Information page?

I know about the hidden folder. I deleted 4 mimeTypes.rdf files on this 4th try to fix.

>Did you use the button on the Help > Troubleshooting Information page?

Yes and if you mean resetting Firefox I mentioned that I did so in earlier attempts and have done so again.

The problem still exists. It seems like a major bug that needs fixing.

Thanks for your help.

What is the Mailto setting in Tools > Options > Applications?

• https://support.mozilla.org/kb/change-firefox-behavior-when-open-file

You can also check the network.protocol-handler.external.mailto prefs on the about:config page.

• http://kb.mozillazine.org/about:config

If network.protocol-handler.external.mailto prefs are user set (bold) then right-click and Reset them to the default value.

>What is the Mailto setting in Tools > Options > Applications?

This menu path doesn't exist on a Mac. Are you using a Mac?

Sorry about the confusion.

On Mac you can find them in Firefox > Preferences > Applications

YooHooo!! That finally fixed it!! It was set to Firefox (default). I changed it to Gmail, which is what I use, and no more millions of tabs!!

Thank You for being so persistent and helpful!

You're welcome.