New to Java

Using the java for chat hasn't been an issue until recently, for one chat site and one alone, the java won't load. I've been on the website FAQ and i've read the causes and solutions but they don't make sense to me. In the internet options the box i have checked and have always had checked is automatically detect settings, i'm a little confused as to why it isn't working.
In the java console i get this message :

load: class com.diginet.digichat.client.DigiChatApplet not found.
java.lang.ClassNotFoundException: com.diginet.digichat.client.DigiChatApplet
at sun.applet.AppletClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadCode(Unknown Source)
at sun.applet.AppletPanel.createApplet(Unknown Source)
at sun.plugin.AppletViewer.createApplet(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: open HTTP connection failed.
at sun.applet.AppletClassLoader.getBytes(Unknown Source)
at sun.applet.AppletClassLoader.access$100(Unknown Source)
at sun.applet.AppletClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
... 10 more
Any help or suggestions would be greatly appreciated.
Thank you
Lola