I assume you have sun jre (the real java? You have to install this in the new Ubuntu by adding the repository.) Ubuntu also comes with openjdk, which is the open source version of java. OpenJDK is getting better, but it doesn't quite open up everything yet, so I suggest you go to the Synaptic Package Manager and uninstall openjdk and the icedtea plugin. This will leave only the sun jre to open java apps.
Hope this helps!
I am a Ubuntu Linux 10.04 user and the Java 6 plug-in doesn't work this site. I have Firefox 3.6.7 and the lastest Java 6 plug-in. See screenshot below the post for more info.
I would like to know if any other Linux users are having the problems and a soution it.
Thanks
Svetla