If you are using Mozilla
http://java.mozdev.org/java_xpis/
Read the version you need and delete the current plugin that is not working before installation
After installation, if you prefer to use Konqueror,
add the Mozilla Plugin directory which will be /home/your-name/.mozilla/plugins
via Settings Configure Konqueror. After adding the path hit the scan for new plugins button.
Hope that helps this time.
I have configured Konqueror to open Mozilla for web page viewing so you can guess which I prefer.
I have also setup up pdf files to open in acrobat reader separately - acroread %u
Larry