Might be a corrupted profile. You can try a fresh profile to see if that's the case by setting up a new one alongside the current one, then using it for a while. You'll find info on how to do this in the Mozillazine support document "Creating a new Firefox profile on Windows". If a fresh profile works for you, you can then migrate your old user data to the new profile. You'll find info about that on the Mozilla Support page "Recovering important data from an old profile".

thanks but I've done this for every version - no difference !

Some crash reports could help. Please follow the steps below:

1. Enter about:crashes in the Firefox address bar and press Enter. A Submitted Crash Reports list will appear, similar to the one shown below.
2. Copy the 5 most recent Report IDs that start with bp- and paste them into your response here.

More information and further troubleshooting steps can be found in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

sorry - do you mean just the bp refs or the whole report ?

Just the Report IDs that start with bp-xxxxxxxx

bp-6a82b14c-172e-461c-ba02-e8fb62131113 bp-52e63c5e-c61c-4383-ac3f-cecb62131113 bp-93043904-5373-4fa5-8c90-7ea782131113 bp-0c17dd6e-0526-49ff-acc3-0f8f12130930 bp-5f960a09-1740-4d1d-82fe-856cb2130930

Your crash reports all show the crashing thread to be mfplat.dll which is a Windows Media Foundation Platform file. All of those crashes also refer to Bug 858667 NEW --- [Win7] crash in mozilla::wmf::MFTEnumEx @ EnumSoftwareMFTs

Try disabling the media.windows-media-foundation.enabled preference in Firefox to see if that stops the crashes (this workaround was reported in the bug report)

1. In the address bar, type about:config and press Enter. The about:config "This might void your warranty!" warning page may appear.
2. Click I'll be careful, I promise!, to continue to the about:config page.
3. Search for media.windows-media-foundation.enabled
4. Double-click the setting to change its value to 'false

Does that help?

Something else I noticed:

Your crash reports Modules list indicates Trusteer Rapport software is installed. You could also try stopping Trusteer Rapport software from running, since it's known to cause crashes in Firefox.

Go to "Start->All Programs->Trusteer Rapport->Stop Rapport"

Ref: http://kb.mozillazine.org/Firefox_crashes#Trusteer_Rapport

Thanks. Ok will try the media player fix but cannot disable Rapport as its important for my online banking. It also works fine with vers 19.... Media player has stopped working properly recently - crashes if you pause it or stop half way through a video. So its been uninstalled & reinstalled & uninstalled but still the same issues...

media.windows-media-foundation.enabled - this key is not present.

I really don't understand why the crashing problem has started as I've used FF for over 5 years now without any problems.... Only since the update from ver19 have I had issues on this Pc. I use it on another 5 Pcs too & all the updates have been Ok....

Which Firefox version are you currently using?

Try to disable hardware acceleration in Firefox.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Hi xraytod, media.windows-media-foundation.enabled was a new preference in Firefox 20 and later. Firefox 20 was the first version that could use that component of Windows to decode MPEG media using the native video player (for patent/license reasons, these codecs can't be built into Firefox). If you can start Firefox up to your home page without incident in Firefox 20-25, then you could change the setting at that point.

I do wonder, though, whether you might need to repair this component of Windows at some point anyway. I'm not sure exactly how to do that. Maybe the System File Checker? You could try to get support on that from Microsoft's forums or another Windows forum.

Thanks Jscher. Every version of FF since 19 will go to home page (google) ok its when I go to say BBC.co.uk (which has media embedded) that it crashes. Have tried SFC & even re-installing win7 but zero difference to FF (or media player) so I guess there must be some connection - but Ive been trying to solve this for months now ! Anyway Uk time is now late bedtime so I'll have to leave until tomorrow !

You wrote,
media.windows-media-foundation.enabled - this key is not present.
It wouldn't be present in Firefox 19 since it was first added to Firefox in Firefox 20 and is enabled by default in Firefox 21 and later. Try updating Firefox, then turn off that preference. Ref:

• Bug 799315 - Windows Media Foundation backend for media playback
• http://kb.mozillazine.org/File_types_and_download_actions#Built-in_support_for_certain_media

You also wrote,
Media player has stopped working properly recently - crashes if you pause it or stop half way through a video. So its been uninstalled & reinstalled & uninstalled but still the same issues...
I'm assuming this is Windows Media Player? Firefox will use an external application such as Windows Media Player (or a plugin, for embedded content) if the media can't play in Firefox. In current Firefox versions, Firefox uses the Media Foundation framework included in Windows to handle certain audio and video by default. Make sure your Windows 7 is fully updated, including Service Pack 1 (this worked for another user with problems playing MP3 content - see /questions/974045).

P.S. If Windows is already fully updated with Service Pack 1 and later updates, and Windows Media Player is still not working properly or crashing, you should get help on a Microsoft or Windows forum, like jscher2000 suggested. You could try one of these forums:

• http://answers.microsoft.com/en-us/windows
• http://windowsbbs.com
• http://www.sevenforums.com

Many Thanks Alice & Jscher. Disabling the media windows media foundation key appears to have solved the problem ! I am now running vers 25 without failure for over 2 hours..... Previously it crashed after seconds.. Now I just need to sort out media player ;)

Hey, that's great! I marked my 11/13/13 answer with the steps to set the media.windows-media-foundation.enabled preference to false in about:config as the solution.

Good luck with sorting out Windows Media Player.