I receive the error message "Your browser must have Java enabled to use the Client for Java." when attempting to load a webpage. Java has been added to firefox and the appropriate checks have been made under preferences.
Another option would be to try to use the Opera browser. Opera works differently from Firefox, Firefox needs the sun-java-plugin package but Opera uses the sun-java-jre package.
Enabling Java for Firefox
Follow the instructions from: http://linux.digitalsp.com/2009/07/install-java-plugin-for-firefox-ubunt...
Let me know if this worked for you.
Another option would be to try to use the Opera browser. Opera works differently from Firefox, Firefox needs the sun-java-plugin package but Opera uses the sun-java-jre package.