Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

While in Safe Mode,

In the address bar, type about:crashes<enter>. Note: If any reports do not have BP in front of the numbers/letters, click it and select Submit.

Using your mouse, mark the most resent 7 - 10 crash reports, and copy them. Now go to the reply box below and paste them in.

If you can't get Firefox to open, you will have to do this the hard way. https://support.mozilla.org/en-US/kb/mozillacrashreporter Open the file browser / explorer on your computer. Note: You may have to enable Show Hidden Folders / Files. Enter this in the address bar;

Windows: %APPDATA%\Mozilla\Firefox\Crash Reports\submitted Win 7/Vista: C:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Crash Reports\submitted Win XP/2000: C:\Documents and Settings\<username>\Application Data\Mozilla\Firefox\Crash Reports\submitted

Mac OS: /Users/<username>/Library/Application Support/Firefox/Crash Reports/submitted Linux: /home/<username>/.mozilla/firefox/Crash Reports/submitted

Copy the last 5-7 Recent File Names in the folder. Post the information in the reply box below.

I cannot start Firefox in safe mode either. When trying to start in safe mode I get the same error message that firefox is running but not responding. I have been using Chrome to get on the internet. I found the crash report and there is nothing within the time frame since the problem began. The most recent files are from 2-7-15 and they are DMP and EXTRA files all starting with a c02 or c2c. All other files are from last year (2014).

As a test, disable your security software. If you want, unplug your modem. Then try starting Firefox.

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

When you say Firefox crashing at startup, are you getting the Mozilla Crash Reporter dialog and submitting crash reports, or the Windows crash dialog?

To kill a Firefox process that did not start up correctly, you can use the Windows Vista Task Manager. Press Ctrl+Shift+Esc to start the Task Manager. Then:

• On the Applications tab, look for any instances of Firefox. If you find one, select it and try using Switch To. If that doesn't work, try using End Task.

• On the Processes tab, look for firefox.exe (if you have a lot of processes running, you can click the Image Name heading to sort by name). If you find it, select it and click the End Process button.

Once there are no Firefox processes showing in Task Manager, then try starting Firefox in its Safe Mode by holding down the Shift key while double-clicking its icon. Can you get it started?

Thank you guys for responding. The error message appears to be a windows generated, so several days ago I already used task manager but found no instance of Firefox in the applications tab. In the processes tab I did already click firefox.exe and end process with no result. That's what doesn't make sense to me. If windows says Firefox is already running it should show up in task manager but it doesn't. Firefox still will not open in safe mode or normally.

Tim7 said

In the processes tab I did already click firefox.exe and end process with no result.

Do you mean the process cannot be killed, or that even after killing the process, Firefox will not start?

When I click "end process" nothing really appears to happen. The file is 64K and properties are C:\Program Files\Mozilla Firefox\tobedeleted. That is the only instance of firefox I see anywhere. And that is correct. I "ended" the process and Firefox still will not open. I also disabled all security software and Firefox will not open in safe mode or normally.

Did you try the computer in Safe Mode?

• 1 Download Firefox Full Installer For All languages And Systems {web link}
• 2 Uninstall Firefox from your computer {web link}
  DO NOT remove your profiles.
• 3 After, reboot the computer.
• 4 Use a Registry Cleaner. Reboot again.
• 5 Then run the full installer.

Hi Tim7, we had some reports in Firefox 36 of firefox.exe being "unkillable" after the browser seemed to become frozen waiting for the network. I thought this was fixed by now... Some of those threads for possible reference (none had a satisfactory explanation):

• Firefox cant connect to the internet after a while of being on
• Firefox stops working after some time
• firefox.exe cannot be killed (terminated) at all except by restarting computer (Windows)

In the first (older) thread, the problem did not occur in a new Firefox profile, suggesting that something in the settings folder (a preference, a corrupted or locked settings file, an extension, something else..) could be the culprit.

Here is how to test for that:

Create a new Firefox profile

This is in addition to and does not replace your existing settings.

A new profile will have your system-installed plugins (e.g., Flash) and extensions (e.g., security suite toolbars), but no themes, other extensions, or other customizations. It also should come with completely fresh settings databases and a fresh cache folder.

Exit Firefox and start up in the Profile Manager using Start > search box (or Run) -- type or paste the following and press Enter:

firefox.exe -P

Don't delete anything here.

Any time you want to switch profiles, exit Firefox and return to this dialog.

Click the Create Profile button, assign a name like May9, and ignore the option to change the folder location. Then start Firefox in the new profile you created.

It might take a while to determine whether the new profile works better than your old one. If you want to import your bookmarks from your regular profile during that time, here's how:

You can use the Library dialog (Ctrl+Shift+b or "Show All Bookmarks") to access the Restore feature. The trick is knowing where to find your bookmark backups in your regular profile. After clicking Choose File... you can paste this into the file name space and press Enter to drill down to your profile folders:

%APPDATA%\Mozilla\Firefox\Profiles

The semi-randomly-named folder that has your last backup is usually the one ending with "default". Click into that one, then into the bookmarkbackups folder. Here you can pick the most recently updated file to restore.

Important: using Restore wipes any bookmarks in the Firefox profile you restore it to, and replaces it with the contents of the restored backup.

Thanks again for your responses. Until now I haven't had time to test anything and was using Chrome to get by. I did finally start the computer in safe mode and was able to open Firefox. I restarted the computer normally and Firefox has opened fine ever since. I did nothing else in terms of troubleshooting. It just started working.

It could have been a corrupt file was replaced.

Please flag your last post as Solved Problem so others will know.