Make Java work in Portable Firefox?

Hello, I am running Firefox Portable and trying to get Java to work. It works perfectly in Internet Explorer; I just prefer to use FF. I tried opening the control panel, going to Advanced, and checking the Mozilla Family option under Default Java for Browsers, but every time I click "Apply" and then "Okay" it seems to reset itself. In other words, every time I check to see that the option has been enabled, the Mozilla Family option is unticked. I've tried choosing the option several times, but it keeps resetting. I don't know if that's the only reason Java won't work, but it sure is frustrating! Any advice?

 

I know this is old but there seems to be more interest in Portable Apps and this thread turned up while I was looking for more info on the subject myself, so maybe others will end up here.

Portable Apps now has a Java portable version on their site:
http://portableapps.com/apps/utilities/java_portable

At the moment, the version listed is 6v19 but Sun have recently released 6v20. Since the installation downloads from the internet during the install, this had me wondering what version of Jave I would end up with. It turned out to be 6v19 sadly. I'm not sure at this stage how to update it to 6v20 or whether I just have to wait for the new one to be made available in portable format.

They also have a Java launcher for Java Jar files:
http://portableapps.com/apps/utilities/java_portable_launcher