Do you face any problems while watching youtube videos on mozilla firefox, Error message "check whether JavaScript turned off " , flash player problem , and some other.? Some times it says " Hello, you either have java script turned off or an old version of Adobe flash player". Really sucks!! This problem may not be fixed by installing flash player by a proper method. It wont play videos until you re install the flash player with a correct flash player installer. first you should uninstall your flash player completely and then install a fresh copy of flash player. This can be done by an installer and and an uninstaller.