Press the Alt or F10 key to bring up the tool bar. Followed by;

Windows; Tools > Options Linux; Edit > Preferences Mac; application name > Preferences

Followed be Applications.

On the left side, look for mailto and check it's setting.

I'm on a Mac. The F10 key mutes my speakers, that's all. What toolbar am I supposed to bring up? I checked Preferences for both email and firefox, and there's no "mailto" on either.

Mac; application name > Preferences

or

Open a new tab or window. type about:preferences in the address box and press enter

I know how to find the preferences. It's the rest of the instructions that make no sense. There's no "mailto". The latest update of Firefox is clearly buggy, because my no-squint and zoom don't work properly anymore either.

Do you only get this problem when Firefox isn't running or also when Firefox isn't running?

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

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

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

I only get the problem when Firefox is running. Once opened, I can click through from emails once or twice, but then it stops working. I have to quit Firefox to click through, and then it only works once or twice.