There are two ways to invoke and run Instant Messenger:
Using the Java Plug-in - In this configuration, Instant Messenger is run as a Java applet. To keep the Instant Messenger session active, the browser window from which the applet was launched must remain open and cannot be used to locate any other URL. In addition, the Java plug-in does not allow desktop integration so the Desktop Integration Settings option will not be available from the Settings dialog box.
For more information on how to configure the Java software that enables Instant Messenger, see Chapter 2, Setting up and Launching Instant Messenger.