Try to uninstall and reinstall Flash. *http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html You can find the latest Flash player versions for Firefox on this page: *http://www.adobe.com/special/products/flashplayer/fp_distribution3.html *http://www.adobe.com/support/flashplayer/downloads.html ---- 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