Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

• https://support.mozilla.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

See:

• http://kb.mozillazine.org/Firefox_crashes
• https://support.mozilla.com/kb/Firefox+crashes
• https://support.mozilla.com/en-US/kb/latest-firefox-issues

Unfortunately, the latest Firefox update has seemed to create issues for certain individuals. The most recent, and current list of latest Firefox issues reported by users, including detailed information, and possible solutions can be found here.

https://support.mozilla.com/en-US/kb/latest-firefox-issues

OK, firefox is working in any account except mine. So, I asume, the reason is some file or data in my account, but what? For that, generate a new profile in my account didn't work. I can invoke 'firefox.exe -ProfileManager' and define a new profile, but starting it will crash firefox. Next question: What files are important for firefox in a user account. I want to rename them to find out, what cause this crash. At least I found (this is a geman version of installation):

Directory username\Lokale Einstellungen\Anwendungsdaten\Mozilla

Directory username\Application Data

Directory username\Anwendungsdaten\Mozilla

Are there any other data or file, needed by firefox in any other location? Thanx!

Personally, the easiest & quickest method for myself would be to completely uninstall firefox completely using a third party uninstaller such as Revo, a free program I have used for years. The built in windows add/remove is marginal at best and often leaves traces of files or folders on the harddrive & registry therefore you will never get a complete clean uninstall, and install.

As I mentioned the program I have used for years is free, and it first uses windows or firefox in this case built in uninstaller to remove, and then proceeds to scan your hard drive & registry for leftover information. This allows complete removal of stored or hidden profile data or preferences that could possibly interfere with new install.

Visit the following link & download the third party uninstaller Revo & run as I previously mentioned.

http://download.cnet.com/Revo-Uninsta.../3000-2096_4-10687648.html?tag=mncol;1

Next download the latest version of Firefox and perform clean install, this should fix any corrupt profile data & useragent localization data and file errors.

http://www.mozilla.org/en-US/firefox/fx/

Thanx! Now I uninstall firefox with this tool, install it again and it crashed as before. But uninstall and install I did as admin. Next try, uninstall (only possible as admin) and install in user mode. Now I can start firefox and it do not crash again. But now I need to manage to find all my bookmarks etc. In which file one can find them? I do not expect firefox will do the job for me (but I will try the link, Swarnava showed me).

BTW it feels good to have firefox running again.