You posted with a Firefox 3.0.15 version and in that version you still have the Edit > Preferences > Content > Java check box.

In Firefox 3.6 the Java plugin is treated just like all other plugins and no longer has a enable check box in Tools > Options > Content.
You can enable or disable all plugins including Java via Tools > Add-ons > Plugins

In Firefox 3.6 and later versions you need the Next-Generation Java™ Plug-In present in Java 6 U10 and later (Linux: libnpjp2.so; Windows: npjp2.dll).

• http://java.com/en/download/faq/firefox_newplugin.xml
• http://java.sun.com/javase/6/webnotes/install/jre/manual-plugin-install-linux.html

ln -s /usr/local/java/jre1.6.0_20/lib/i386/libnpjp2.so libnpjp2.so
ln -s /usr/lib/jvm/jre/lib/i386/libnpjp2.so /usr/lib/mozilla/plugins/libnpjp2.so (java-1_6_0-sun-plugin)

Thank you very much for sending the correct information, the right name of the *NEW* Java plugin ($JRE/lib/i386/libnpjp2.so). Everything works now: Java, my IPMI consoles, etc!

As others may face the same problem, and get also lost looking for the right information, the right link to make, I just want to point out that the "Enable and Configure" information in the JRE download page is out of date. It would be great if it were fixed. It still recommends a soft link to the *old* plugin ($JRE/plugin/i386/ns7/libjavaplugin_oji.so):

http://www.java.com/en/download/help/linux_install.xml#enable

Many thanks again for your great help. Gus

You're welcome

hey, i am damn idiot and your instructions are unreadable - simple request: enable java????