Comment 7 for bug 280064

I have this same problem,

iuri@moeda:~$ update-alternatives --display xulrunner-1.9-javaplugin.so xulrunner-1.9-javaplugin.so - status is manual.
 link currently points to /usr/lib/jvm/java-6-sun/jre/lib/amd64/libnpjp2.so
/usr/lib/jvm/java-6-sun/jre/lib/amd64/libnpjp2.so - priority 63
/usr/lib/jvm/java-6-openjdk/jre/lib/amd64/IcedTeaPlugin.so - priority 1061
Current `best' version is /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/IcedTeaPlugin.so.

But I can correct it by:
sudo apt-get install sun-java6-plugin
sudo update-alternatives --config xulrunner-1.9-javaplugin.so
[selectin here libnpjp2.so]

If I don't do this 'update-alternatives', firefox (via about:plugins) displays two java plugins.

Possible cause: icedtea plugin only adds one alternative (xulrunner-1.9.javaplugin.so) while sun plugin adds many alternatives, so I think that is the problem.

in annex a complete list of alternatives