can't run the groovyConsole

I don't seem to be able to run the groovy console. I get the following stack 
trace...

Exception in thread "main" java.lang.ClassNotFoundException: groovy.ui.Console
        at java.net.URLClassLoader$1.run(URLClassLoader.java:199)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:187)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
        at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassL
oader.java:135)
        at org.codehaus.classworlds.DefaultClassRealm.loadClassDirect(DefaultCla
ssRealm.java:262)
        at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassReal
m.java:239)
        at org.codehaus.classworlds.Launcher.getMainClass(Launcher.java:194)
        at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:371)
        at org.codehaus.classworlds.Launcher.launch(Launcher.java:336)
        at org.codehaus.classworlds.Launcher.main(Launcher.java:461)

I am running this on Win 2K. The JVM is 1.4.2_05. The version of groovy is 
1.0-beta-7.

I had a quick look to see if I could shed any light on the problem. This class 
is not in groovy-1.0-beta-7.jar. I had a peek at the source code. I am guessing 
that this class is produced from the script file groovy.ui.Console.groovy. 

Does anyone know what is going wrong?

thanks,
Andy