I’ve been struggling with lava support for Firefox after upgrading from Ubuntu 7.10 to 8.04. All I had to do was to remove the package called icedtea-gcjwebplugin. Now, I don’t know my way around Java anymore, but at least it did the trick. Worth a shot if you have problems.
John has some more information on this issue if the above didn’t do the trick:
I also needed to link to the new plugin….
sudo ln -s /usr/lib/jvm/java-6-sun/jre/plugin/i386/ns7/libjavaplugin_oji.so