You can uninstall and remove Java Console extensions, you do not need them to run Java applets.<br /> The Java plugin that you see in Tools > Add-ons > Plugins is used to run Java applets. See: * http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions You can also disable the Java Quick Starter extension if you have it. * Tools -> Add-ons -> Extensions * Control Panel -> Java -> Advanced tab -> Miscellaneous -> Java Quick Starter (disable)