Open Firefox in it's diagnostic Safe Mode by holding down the shift key while starting Firefox. Firefox will start with Extensions and a few other things disabled. When done with Safe Mode, exit Firefox, wait a few seconds and click on the Firefox desktop icon to start Firefox in regular mode.

More info about that and manually removing extensions, if necessary, included in the following articles:

• https://support.mozilla.org/en-US/kb/Cannot uninstall an add-on
• http://kb.mozillazine.org/Uninstalling_extensions

Added followup questions:

• Name of add-on?
• Link to where you downloaded the add-on?
• Was it a separate application? If so, have you looked in Control Panel > Add or Remove Programs (or Programs and Features) to see if it is listed and remove from there?

That worked perfectly. The offensive addon has been removed and I am back up again.

Thank you again.

What was the name of the add-on? From where did you download it?

The name of the addon is:

HTTPS Everywhere 

from the Electronic Frontier Foundation website is:

HTTPS Everywhere

I reported the problem to them.

Interesting. I have HTTPS-Everywhere 3.0.4 installed and active in the instance of Firefox 17.0.1 that I have been using to respond to your question and have never had a problem with it. If you are opening a home page to a domain on their list and that item on their list is not functioning properly, it could cause a problem. Hopefully, they will find a solution for you.

My home page is the FF start page.

It might be a conflict with another addon.

Also, after FF looped for a while it later crashed.

The home page about:home is built in to Firefox and should/would not be affected.

Though it should/would not affect about:home, there is an entry for Mozilla on their list, if you are using some page at mozilla as your home page. On my installation that item on their list is shown as disabled; I do not recall disabling that item myself, therefore it could be their default (disabled) and they know that item is not functioning properly on their list.

You may be correct in that there could be a conflict with another add-on. The only way to determine that is to experiment by installing HTTPS Everywhere, disabling/enabling a few extensions (or plugins), restart Firefox and repeat until you find the conflicting item.

• See https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems
• See https://support.mozilla.org/en-US/kb/troubleshoot-issues-with-plugins-fix-problems
• See https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems#w_4-troubleshoot-your-plugins

The only other thing that comes to mind is a possible corruption of HTTPS Everywhere during download/installation.

Post back once you locate a solution yourself, if it is a conflict with another add-on, or once you hear back from Electronic Frontier Foundation with a solution from them.