Hi kisenok1989,
Sorry you are having problems.

Try to give more information about what your device and Operating System is and anything else that seems likely to help.

• If you kill the firefox.exe process & any plugin-container process using your Operating System, leave it a few minutes and try again does that help.
• Is your Operating System logging any related error messages ?
• You would not happen to be using a device that employs finger print recognition would you ?
• Have you used Firefox before and has it worked on the same device?
• Could any security related software be interfering or blocking Firefox, or this version of Firefox ?
  What security related software is in use ?

See also

• Firefox won't start - find solutions
• Configure firewalls so that Firefox can access the Internet
• Fix problems connecting to websites after updating Firefox
• http://kb.mozillazine.org/Browser_will_not_start_up

Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that turns off some settings and disables most add-ons (extensions and themes).

(If you're using an added theme, switch to the Default theme.)

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu by clicking on the Restart with Add-ons Disabled... menu item:


If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

Thank you.

Hello John99.

I have Windows 8.1 installed on my Lenovo G580 notebook.

 "Is your Operating System logging any related error messages ?"

I havent found any logs related to Firefox.

 "You would not happen to be using a device that employs finger print recognition would you ?"

No.

 "Have you used Firefox before and has it worked on the same device?"

I have used Firefox Portable a couple of times and it woirked.

 "Could any security related software be interfering or blocking Firefox, or this version of Firefox ? "

I'm using Avast Free Antivirus. Tried to turn it off, but it didn't help.

This will at least bump the question and someone may give a better answer.

In relation to Avast you said Tried to turn it off, that makes me wonder if you did manage to disable it or not. Also did check Avast's settings. I did at least find an article suggesting some Avast software could cause this sort of problem

• Problems With Avast & Firefox Not Starting http://smallbusiness.chron.com/problems-avast-firefox-not-starting-...

Do you still have Firefox portable ?

• does that still work ?
• What Firefox version is that ?

I do not use Avast but any chance your Avast software, or Firewall is blocking the current Firefox Release, but is set to allow Firefox portable.

Try starting Firefox in Windows safe mode that may help as it may stop some other software interfering

• http://www.bleepingcomputer.com/tutorials/start-windows-8-in-safe-mode/

As you know the process is running but the screen is not appearing it is hanging for some reason. Does the following article help ?

• Firefox hangs or is not responding - How to fix_firefox-hangs-while-loading-the-first-window
  Scroll the article to see the other suggestions.

Thank you for assistance John99.

I have found out that it actually launches, but it takes about 10 minutes to show the window. Starting Windows in safe mode doesn't change the situation. I have also added Firefox to Avast's exclusions list as suggested in the article.

So Firefox actually works but it starts too long

Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

Download a fresh Firefox copy and save the file to the desktop.

• Firefox 27: http://www.mozilla.org/en-US/firefox/all.html

If possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.

• Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you lose personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
• (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.

If you keep having problems then also create a new profile.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall