Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

To Enable SafeMode

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.
• Once you get the pop-up, just select "'Start in Safe Mode"

If it works in Safe Mode and in normal mode with all extensions (Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: "Firefox > Quit Firefox"; Linux: "Firefox/File > Quit")

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Safe Mode had no effect. Sorry for omitting detail in initial post. I watched it go from working in Ver 8.0 to failing in Ver 24.0 in a matter of a few minutes on my laptop as Firefox was going through automatic update. There were no other changes at that time to the laptop. Desktop and laptop are on ver 24.0 and it fails on both.

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

Do you have a problem with a secure connection or blocked content indicated via an icon on the left hand side of the location bar?

If you get an untrusted message then check out why the site is untrusted (click "Technical Details to expand that section) and if this is caused by a missing intermediate certificate then see if you can install this intermediate certificate from another source.

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button and inspect the certificate and check who is the issuer of the certificate.

You can see more Details like intermediate certificates that are used in the Details pane.

If "I Understand the Risks" is missing then this page may be opened in an (i)frame and in that case try the right-click context menu and use "This Frame: Open Frame in New Tab".

None of this is relevant as far as I can tell. I am the webmaster and this is the main index.html page for the website I maintain. As far as I know, there are no certificates or iframes on the website. I don't have a problem with a secure connection but I get a message that says that the data is encrypted but the communication line is not secure and the content could be read by others. This is not a problem and I reply <continue> to the message box just like always. A screen shot would just show the endless "loading" in the upper left corner. Unless you can see something there like a hidden message in the little spinning gear wheel, I will respectfully decline the effort to produce a screenshot.

Hello,

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

Thank you.

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page.

Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious and if you have a password or other data from that domain that you do not want to lose then make a note of those passwords and bookmarks.

You can't recover from this 'forget' unless you have a backup of the involved files.

It doesn't have any lasting effect, so if you revisit such a 'forgotten' website then data from that website will be saved once again.

why not use control panel, programs and features, and just let Windows uninstall it? I can then simply download and reinstall a new version. One other point I forgot to mention in all of this: The problem does not happen when using Chrome. This is not a solution to me because the product should work in every browser and I am philosophically opposed to doing business with a company whose stated security policy is that it will share everything it finds out about you with everyone it wants.

Maintaining my website is the ONLY thing I use Firefox to accomplish. As far as I know, there is nothing in Firefox about anything I have. I will probably try the uninstall and reinstall that the other person recommended.

Could be relevant: HTML Editor not working from cPanel - HostGator Peer Support Forums - "All I get in the editor is the html rendered as a page with no style." Problem with mixed content blocker enabled in Firefox 23 (more info: Mixed content blocking in Firefox) That can be disabled manually in about:config if necessary.

set both security mixed content ... to false. Everything seems to be working OK