When you want to run the ULC UI Engine as an applet you need a browser with JDK 1.2 support. The currently supported Web browsers for running the ULC UI Engine as an Applet are Netscape Communicator 4.x and Microsoft Internet Explorer 4 or 5. The browser must also have the Java Plug-in 1.2.2 installed.
You can verify that the browser opens the applet successfully by opening the Java Console. If your browser doesn't have the required JDK support the console will show a corresponding exception. If you have no such browser available you can still run the UI Engine using the Java Runtime Environment (JRE) and in this case no HTML browser is needed.