Sorry to hear that.

You did not supply any information as to what OS & version # that that was running on. If you could next time please.

I gather than your not worried about your bookmarks and passwords and profile ? If are do not pull any more folders. Or there is more to pull. Pick one. You could also dive into the registry and delete Mozilla also.

Try installing from a Full Version Installer : https://www.mozilla.org/en-US/firefox/all/ And if this is on a older system and older OS you may want to go to the Extended Release Version : https://www.mozilla.org/en-US/firefox/organizations/

I hope one of these Full Version Installers will do the trick to fix yuo.

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

Thank you for the reply. I'm using Windows 7 Professional, and the latest version of Firefox, 56.0.1.6484.

And yes, I'd love to be able to keep my bookmarks/passwords/preferences if it's possible to do so. Do I have a profile folder somewhere that I can copy and rename? I'd like to try that before doing a new install...

Firefox comes in two or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user folders would not be affected.

+Win Firefox uses two locations for the Firefox profile folder. Location used for the main profile in "AppData\Roaming" that keeps your personal data.

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\

Location used for the disk cache and other temporary files in "AppData\Local".

• C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profile

Hi - I've removed my old profiles folder (and renamed it) and have tried a clean install of Firefox. Same issue. The process firefox.exe starts for about 2 seconds and then closes. The software doesn't open. Not sure what else to do.

So you installed with the Full Version install from 1st post ?

Ok so back to this : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Reinstall with Current Release Firefox 57.0.1 with a Full Version Installer https://www.mozilla.org/firefox/all/

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.

Windows 10 To run the DISM command use the Windows key + X keyboard shortcut to open the Power User menu, then select Command Prompt (Admin). Type "DISM /Online /Cleanup-Image /RestoreHealth" (without quotes or copy/paste) and press Enter. Reboot After.

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.