If you have a recent update to java on your computer, the java applets may not run. If you get a message that you can't access an applet, trying going into the Java Control Panel from the Start menu
In this Java control panel, select the Security tab and move the Security Level to medium.
You may still be asked to "accept the risk" when you run the applet, check the box and press Run.
You may want to change the setting back when you are finished with the applet.
If your control panel does not show the Security Level lever, you may need to remove older versions of java from your computer first.