Let’s do a full clean re-install;

Download Firefox For All languages And Systems {web link}

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86)

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Do Not remove the profiles folder.

Look for, and rename any Mozilla or Firefox program folders by adding .old to them. Do not rename the Mozilla Thunderbird folder if there is one.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. If all goes well, remove the OLD folders when you are done. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode This shows how to Start all Computers in Safe Mode; Free Online Encyclopedia

I did exactly as you said but I am still getting the same problem

Try uninstall/deleting all the folders as was pointed out but downloading Firefox Full Version Installer from here : https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

Just followed your last lot of instructions and still getting the same problem

What's your computer system and Firefox version?

It’s Windows 7 and I downloaded the full version that you guys suggested in the last email/message you sent.....Firefox for all languages and systems

https://support.microsoft.com/en-ca/help/904708/fix-you-may-receive-a-the-memory-could-not-be-read-error-message-or-a Sorry unless have a 2003 server does not apply, but close. Please do the below though.

http://www.thewindowsclub.com/diagnose-and-troubleshoot-basic-problems-with-directx

Repair System Registry and Files

(FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN)

To run the SFC command use the Windows key + X keyboard shortcut to open the Power User menu and select Command Prompt (Admin). Type "SFC /SCANNOW" (without quotes or copy/paste) and press Enter. For more information on using SFC, please refer to the Microsoft KB: Use the System File Checker tool to repair missing or corrupted system files

Run the Windows Deployment Image Servicing and Management (DISM) and System File Checker (SFC) tools as Administrator. The DISM and SFC tools scan the integrity of the Windows image and all protected system files replaces corrupted, damaged and incorrect versions. (FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN) Type "DISM /Online /Cleanup-Image /RestoreHealth" (without quotes or copy/paste) and press Enter.

Note : SFC fixes files locally using files found on your system. Note : DISM goes up to Microsoft for new ones.

Please let us know if this solved your issue or if need further assistance

I am still getting the same message after your last instruction

That is too bad. Wonder if you do have a memory module that is bad. If you download this and make it a bootable disk and run it will check your ram for you. 5 passes should be enough I think https://www.memtest86.com/download.htm

It’s all getting too complicated for me now! I think I’ll just have to give up...I’m gutted as I use Firefox for work and it really was the best for what I do.