I assume these sites use Flash. Please see all articles below. * [[Flash Plugin - Keep it up to date and troubleshoot problems]] * [[Flash 11.3 crashes]] * [[Flash 11.3 doesn't load video in Firefox]] * http://forums.adobe.com/thread/1018071?tstart=0 * http://blogs.adobe.com/asset/2012/06/inside-flash-player-protected-mode-for-firefox.html - You may want to try to disable protected mode as its a high source of crashes and freezes of flash.

Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance). *Do NOT click the Reset button on the Safe Mode start window. *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes ----- Note that your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox. The user.js file is only present if you or other software has created it, so normally it wouldn't be there. you can check its content with a plain text editor if you didn't create this file yourself. The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session. *http://kb.mozillazine.org/Preferences_not_saved