No page on the site will ever load in Firefox (you could test various pages by clicking through some results from your favorite search engine)?

Could you also try visiting the site in Firefox's Safe Mode? That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled

In the dialog, click "Start in Safe Mode" (not Reset)

Any difference?

Thanks jscher2000. Yes, in Safe Mode I was able to go the site. I read the possible ways that Firefox suggests to try to fix the problem, i.e., go through all my extensions to find the problem or reset Firefox to the original factory settings. Where do you suggest I go from here?

The Firefox Reset feature is a great shortcut, but since you have a lot of extension that you may not want to set up again from scratch, it might be easier to try a few other things first.

I'd try disabling the first half of your extensions (names starting with A-M), restart Firefox, and see whether the site site loads. Continue the elimination test (e.g., re-enable or disable half at a time, then half of the half, etc.) until you get a better fix on which extension might be the problem.

Safe Mode also disables some customizations, but while those could affect page layout, they seldom block a site completely.

I would at least also try to reset all network prefs on the about:config page.

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

Note that your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there. You may want to check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so involved preferences can only be changed temporarily for the current session.

• http://kb.mozillazine.org/Preferences_not_saved

I found that "https Everywhere" was the problem extension. I know the site is safe. The site is www.lef.org. Is there anything else that can be done so I can keep "https Everywhere" enabled or do I just have to disable it every time I want to go www.lef.org? Do you think "https Everywhere" is a worthwhile extension in the first place?

HTTPS Everywhere makes it convenient for you to switch sites to a secure connection. This is something you can do yourself on sites where you are posting sensitive information, so while it automates this for you, I think it is not essential.

If you like the convenience, the extension has a feature to create your own rules, as described on https://www.eff.org/https-everywhere/rulesets. It sounds a little complicated...

Thank you. As it turns out I was able to find the subject website in the HTTPS Everywhere extension under "Enable/Disable Rules". I unchecked the subject site and now I can connect to the site. So I'm now able to go to the subject site while keeping the HTTPS Everywhere extension enabled, which is good.