[GeForceTony]

OK, tried it via the command prompt, and this is what I get:

C:\Temp>java -jar Updater.jar
Exception in thread "main" java.lang.UnsupportedClassVersionError: Bad version 
number in .class file
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(Unknown Source)
        at java.security.SecureClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.access$100(Unknown Source)
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClassInternal(Unknown Source)

This is using either Java 1.5.0.12 or Java 1.6.0.2 (the latter is the latest version available from Sun)

Also happens in either Windows XP or Windows Vista, and on 3 different computers, (my 2 and my friends, at a different location). I also made sure that port 88 is open and available, and it is.