Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

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

SECOND _ Check your volume output settings What to do if Firefox won't play any sounds

Do you have an intel microprocessor?

Flash Player Note: Windows users should download the ActiveX for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the ActiveX.

Flash Player Version: Version 27.0.0.183

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download. <Windows Only>

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download. <Windows Only> +++++++++++++++++++ See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

Sorry guys, tried both the safe mode and that made no difference. Then installed flash for both FF and IE (strange that I should have to add the flash for IE when using FF?) but still no success.

I can see that the volume is a giveaway and checked carefully the settings in the volume mixer but it's not muted and the sound is up, so don't see anything I can change there. I find it annoying that there is no pop-up/alert or warning by FF to give any indication that it stops something. I wonder if there is a setting under config that I might have touched in the past and that is still having this effect. Is there any "go back to default" setting for FF that I could try that would ensure that any settings under config or add-ons go back to normal? Since I am running the program basically without add-ons anyway, I am not sure what other setting I can look at. FF 57 is indeed fast but switching to another browser just to see some newsclip in Chrome is somewhat silly.

The flash IE plugin is in case you need to use IE.

Firefox now comes with a built-in HTML player. But some sites still use flash.

Please provide public link(s) (no password) that we can check out. No Personal Information Please !

Both sites you linked to are using a HTML5 player and not using the Flash Player Plugin from Adobe.

A site you can use to see if you system fully supports HTML5 is https://www.youtube.com/html5/ as all checkmarks should be blue.

Just because the pages works in Chrome does not necessarily mean it is a issue with your Firefox as Chrome cheats with it's own codecs for HTML5 player.

Do you by chance have a N or KN version of Windows 7? as if so then either you did not install a Windows Media Feature Pack for needed codecs or a major Windows updates made it so you have to install it again.

https://support.mozilla.org/en-US/kb/fix-video-audio-problems-firefox-windows

@ Fred - the sites were listed in my original post though they are just examples - at present youtube is basically useless as is radio streaming

@ James - doing the test on the site you suggested, I am getting tick marks for everything except for MSE & WebM VP9 (not sure what that means) - do the sites in question require this feature?

as for the type of version I am not sure what N or KN stands for - my version is Win 7 Prof/ 64 bit -

https://support.microsoft.com/en-ca/help/13443/windows-which-operating-system

http://blog.bitcollectors.com/adam/2013/03/windows-vista-and-7-n-k-kn-special-editions/ Windows N: Has multimedia support removed from the OS install. This is the version sold to the European market and is missing Windows Media Player, Windows Media Center, and Windows DVD Maker. This was due to sanctions by the European Union (EU) against Microsoft for violating anti-trust laws.