This link will explain why the applet does not work on some Browsers
http://java.com/en/download/help/redximage.xml

Start the "Java Plug-in Control Panel" by following these instructions.

Click the Start menu
Select Settings
Select Control Panel
Double click the "Java Plug-in" icon
Click the "Proxies" Tab

Check that "Use Browser" is selected in top left

Then check that all Browsers are enabled

Close the plugin dialog and try the webpage again...

The link page above provides much more info with regard to setting proxies etc, but the above sorted mine out....