We're sorry to hear that your Firefox seems to be crashing when you open it. Please perform the following steps to give us a crash report ID that helps us find out more about the cause of the crash.

1. Press the following shortcut to get a Run window: [Windows] + [R]. This should bring up a window that contains a text field.
2. In that text field, enter %APPDATA% and press Enter. An explorer window should open.
3. From that explorer window, double-click on the Mozilla folder, then double-click on Firefox and then on Crash reports. Double-click on submitted.
4. Now, you should see a list of files that contain reports. Go to View > Arrange Icons by > Modified to get the most recent files at the top of the window.
5. Open the most recent 5 files with a text editor and copy the IDs.
6. Paste each ID with bp- into the reply window on the forums.

Thanks in advance!

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test to see if that helps.

See also:

• http://kb.mozillazine.org/Firefox_crashes
• https://support.mozilla.org/kb/Firefox+crashes

Here are the IDs, will test Windows Safe Mode later this day. Thanks in advance!

bp-e0141076-3702-4189-b687-e12822130515
bp-9d802747-032a-4032-8ac1-a30872130515
bp-d27b3ee3-d917-468a-9a6e-4bc792130515
bp-168a168f-48b9-4d26-8135-62eef2130515
bp-149e8d89-1727-4be5-a656-a1c5f2130515
bp-f024feee-ee47-42ea-94b3-988b52130515
bp-d074383f-cf04-4ea1-bd4b-caa042130515
bp-ae8eb1b0-dd61-407a-bbe5-6b8f62130515
bp-6541a37b-9ab8-494d-b656-c02012130515
bp-e3fe490c-a16a-4f8f-a7a1-c48752130515

hello DrNo123, does it change when you go into your profile folder & create a new file named user.js with the following content:

// Disable Windows Media Foundation support
user_pref("media.windows-media-foundation.enabled", false);

Note that the user.js file is read every time Firefox is started, so settings stored in user.js will override settings that have been made in the previous session (e.g. via about:config or otherwise in the user interface) and were saved in prefs.js.
You can only change them on the about:config page for the current session and not permanently, so be cautious with using the user.js file to set prefs as you may forget about this.
In such cases you need to make the change in user.js or remove such a user_pref() line to make them work across sessions.

Hello.

Ok, i have placed the user.js in my profile folder and no crash for 5 minutes now, which is a huge improvement.

What exactly does this mean now? Is this the new internal H.264 support which causes the crash if the system remains stable now?

What should I do to ensure that FF works correctly w/o user.js?

Many thanks so far I'll keep in touch to tell you if FF remained stable.

Example which I wanted to add: when opening this XML page I could produce an instant crash of FF21 - which now is gone with user.js and the deactivated MS WMF: http://podcast.wdr.de/radio/presseclubwdr5.xml

Once the pref has been changed to false then it should stay at the false value if you remove the user.js file.

It probably should have been sufficient to set this on the about:config page, but that may not have been possible if Firefox keeps crashing all the time if you use the location bar.

You may need to keep this user.js file to use with a new profile if you ever want or need to use a reset as this creates a new profile that will have the default true value of this pref.

This didn't help for me. I put the user.js file in my profile directory with a copy/paste of the line specified, and it still crashes for me. IE performs fine, unfortunately, which is how I'm able to type in this reply.

hello derrickbj, there are countless reasons why the browser might crash. the solution in this thread is based on issue that got apparent through the crash reports the original question owner has provided.

please follow this guide on how to collect the crash report ids that got sent when your firefox crashed & open a new question for it: Get help fixing this crash