Crashes or other problems with certain multimedia content in Firefox (such as YouTube videos and Flash animations or games) can often be resolved by performing the steps in these Knowledge Base articles: * [[Flash Plugin - Keep it up to date and troubleshoot problems]] * [[Adobe Flash plugin has crashed - Prevent it from happening again]] <!--Please also note that html5 may need to be enabled to view some videos on youtube [https://www.youtube.com/html5]--> Please tell us if this helped!

I did the " Disable Flash protected mode " and did start to work again , in that case I was able to open the setting and uncheck the " hardware aceleration ". Thanks a lot