Exception java.lang.IncompatibleClassChangeError while running Groovy in Eclipse Juno

I have recently downloaded Eclipse Juno and installed latest Groovy plugin.

Now here is how my Groovy file looks like.

package groovy_support

class TimePass {
static void main(def args){
    println "Hello World"
}
}

When i run this from either my previous eclipse version (indigo) or from command line, it runs. On Eclipse Juno, however, it complains with following exception on Eclipse console.

Caught: java.lang.IncompatibleClassChangeError: Found class org.objectweb.asm.ClassVisitor, but interface was expected
java.lang.IncompatibleClassChangeError: Found class org.objectweb.asm.ClassVisitor, but interface was expected

Note that "Groovy Libraries" are already on classpath.

Now what am i doing wrong here?