For users of Windows Vista, Windows 7, and Windows 8, make sure to disable the protected mode feature of the Flash Player plugin. While it has theoretical security benefits, it remains buggy.

See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

More detailed steps if you run into permission issues editing the mms.cfg file:

(1) In a My Computer or Windows Explorer window, open this folder:

C:\Windows\SysWOW64\Macromed\Flash If that folder does not exist, then you are using 32-bit Windows, and you can open the following folder instead:

C:\Windows\System32\Macromed\Flash (Note: This folder exists on both 32-bit and 64-bit Windows, but on 64-bit Windows Firefox uses the Flash player in the SysWOW64 folder instead.)

(2) Check for a file named mms.cfg:

(A) If mms.cfg exists, drag it to your Documents folder where you can edit it without being bothered about administrator privileges

(B) If mms.cfg does not exist, open your Documents folder, right-click > New > Text File and name the new file "mms.cfg" (putting quotation marks around the file name help prevent Windows from tacking .txt onto the end)

(3) Open mms.cfg from Documents into a text editor such as Notepad. Add this on its own line (I put it last):

ProtectedMode=0 Save the file and close Notepad.

(4) Hold down the Ctrl key and drag the mms.cfg file back to the Flash folder to make a copy there, keeping the original in Documents

This change should take effect the next time you exit and restart Firefox.

I actually made a script to edit that file , but something tell me this was already done if you tried everything in these forums?

You can use that script here:

http://firefoxcrash.blogspot.com/2013/12/disable-protected-mode-in-adobe-flash.html

IF you have done this, and have disabled hardware acceleration, created new profile, uninstalled and reinstalled Firefox and flash, then i would suggest an alternate means:

For almost a year now i resolved my firefox/flash player crashes by keeping certain prefetch files cleared. I am not going to say this will resolve your crash, but could. I have a full explanation as well as video about it here:

http://firefoxcrash.blogspot.com/2013/12/firefox-crashes-adobe-flash-player.html

Also alternately you can disable the plugin container. More on that is here:

http://firefoxcrash.blogspot.com/2014/01/how-to-fix-flash-player-crashes-in.html

Please make sure you delete the mms.cfg file mentioned above IF you disabled protective mode. It will not harm anything by doing so or delete the line item mentioned above before disabling the plugin container, as could cause issues if it is set to '0'.

Best Regards

Your solution seems to have worked.