Make sure that Firefox closes properly to avoid session restore from trying to reopen a possibly crashed session.

See:

• "Hang at exit": http://kb.mozillazine.org/Firefox_hangs
• "Firefox hangs when you quit it": https://support.mozilla.org/kb/Firefox+hangs

Try to use "Firefox/File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit") to close Firefox if you are currently doing that by clicking the close X on the title bar.

Well cor-el thanks for trying, but what you gave doesn't works at all :(.

You can check for problems with the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder that store session data.

Delete the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox Profile Folder.

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost, so you will have to create them again (make a note or bookmark them).

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

Thanks again cor-el I did resolved it by a different way already.

Help > Troubleshooting Information > Click on Reset FireFox to it's default status.

I was afraid for my bookmarks and history, and took a backup for my bookmarks and great thing didn't need to restore them.

Once again thanks for trying to help me and hope others will have benefits from his question.

taheralnajjar

Thank you for saving me wasted hours of trying to fix this.

Anybody using this write down your add-ons before doing it.