1. Remove the IcedTea java plugin (libjavaplugin.so or javaplugin.so) link in /usr/lib64/browser-plugins. (or lib for 32 bit systems)
2. Create a link to the sun java plugin in the /usr/lib64/browser-plugins directory:
ln -s /usr/local/java/jdk/jre/lib/amd64/libnpjp2.so libnpjp2.so
(Use your java path)
To make sure your plugin in installed type:
in the firefox address window.
To test the plug-in using a jnlp webstart applet, Click the 'Biorhythm applet' icon on this page:
If webstart stops working, it is probably due to an update adding back the icedtea link. Just delete the link and webstart will work again.