I downloaded Firefox 3.6 for Linux directly from Mozilla's web. I unpacked the files locally in my user domain and Firefox worked right out of the box but it could not find my machine's Java installation. I asked about this in a Frirefox 3.6 thread in the help forum but got no help. It may be that I am the only one with this problem but now that I have figured out how to make it work I write about it here just in case...
You need to manually link to the Java library like this.
First go to /usr/lib/mozilla/plugins for global access or .mozilla/plugins in you user account for local access. Then type
sudo ln -s /usr/lib/jvm/java-6-sun/jre/lib/i386/libnpjp2.so libnpjp2.so
In the local case you do not need sudo.
If you installed FF 3.6 using the package manager and one of the alternative repos out there all this may already be sorted out for you.
I still have a 15g 8.10 partition that i use for some video tasks since that was the end of fglrx support.
Im running abrowser 3.7 from the Mozilla Daily Build Repo's and java runs fine.
To add the Mozilla Repos...
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 247510BE
sudo sh -c "echo 'deb http://ppa.launchpad.net/ubuntu-mozilla-daily/ppa/ubuntu intrepid main ' >> /etc/apt/sources.list"
sudo sh -c "echo 'deb-src http://ppa.launchpad.net/ubuntu-mozilla-daily/ppa/ubuntu intrepid main ' >> /etc/apt/sources.list"
to add to your sources list.
sudo apt-get update, and all the Mozilla beta's and pre alphas should show up in synaptic.