Hello,

Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

Thank you.

If you have submitted crash reports then please post the IDs of one or more recent crash reports that have a "bp-" prefix:

• bp-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

You can find the IDs of the submitted crash reports on the about:crashes page.

• You can open the about:crashes page via the location bar, like you open a website, or open this page via "Help > Troubleshooting Information".

See:

• http://kb.mozillazine.org/Mozilla_Crash_Reporter
• https://support.mozilla.org/kb/Mozilla+Crash+Reporter

I've tried opening Firefox in safe mode, and the same problem occurs.

There is no crash report for the most recent test. The only recent one I can find is from yesterday:

bp-aaf0720c-9f12-4e0b-aaed-0762d2130528

It has to be noted though that I don't think it's a conventional crash, if that makes sense, it's just that opening any webpage with video media causes Firefox to close, rather than crash per se.

That is a problem with Silverlight (npctrl.1.0.30716.0.dll : is that really SL 1.0?), so make sure to update Silverlight to the latest version.
You may have to uninstall the current Silverlight version.

• https://support.mozilla.org/kb/use-silverlight-plugin-play-audio-and-video

I've checked on the Silverlight plugin website, and it says the following:

The version of Silverlight installed is: Silverlight 5 (5.1.20125.0)

You are ready to use Microsoft Silverlight

This suggests to me that Silverlight is up to date, and checking the plugins in Firefox tells me the same, so I'm confused.

Could it be somehow that Firefox isn't recognising that the plug in is up to date when loading web pages?

You may have an older version of this plugin.
I'm on Linux, so can't check how this plugin is reported and you didn't attach the installed plugins.

You can inspect the pluginreg.dat file in the Firefox Profile Folder to see the path of this plugin file and where it is located.

You can try to delete the pluginreg.dat file in the Firefox Profile Folder and maybe addons.sqlite as well to reset the plugin registry databases.

See Re-initializing the plugins database:

• https://support.mozilla.org/kb/troubleshoot-issues-with-plugins-fix-problems

Thanks for the help so far.

I have now checked the plug ins, and I've found that disabling the Shockwave Flash plugin solves the problem, but, of course, I can't play any video content with that disabled.

I've checked at the flashplayer site, and I have the latest version, so I don't know what to do.

I read through the link in your post above, but obviously I don't want to uninstall it permanently, because I need it, so do I have to uninstall, and then re-install? Or is there another option I could try first?

Problem solved! I downloaded and installed Firefox 24.0 Beta. Apparently Mozilla programming team made all the right changes in the new release. Now all videos starting working and do not close unexpectedly on Yahoo and BBC.

Link: http://www.mozilla.org/en-US/firefox/channel/#beta