Verify that Java is installed on your machine by checking "Start->Settings->Control Panel->Add Remove Programs" dialog. If Java is installed then you will see “Java Runtime Environment” in your list of installed programs. If Java is not installed then install Java by following the instructions below continue with the next step.
If Java is installed then make sure that Java is enabled by checking your Internet Explorer settings. Open an Internet Explorer window, select "Tools/Internet Options/Advanced/Java menu", and verify that the Java (Sun) checkbox is selected. If you still experience problems then, please, contact your system administrator.
Verify that your Java applet has enough memory for the registration applet by checking "Start->Settings->Control panel" dialog. From the dialog, select "Java Plug-in" and double click on it. Click on the advanced tab and enter "-Xmx256M" into the edit box labeled as "Java Runtime Parameters". Close all your browsers, and try to access the specified NCSA web page again.
The installation process for Java Runtime Environment (JRE) is described below: