Problem with Run as Groovy Script

I have eclipse 3.5.1 with the groovy plugin snapshot from 10/28.

I have a small groovy script that I'm trying to run with the eclipse debugger (by clicking Debug As -> Groovy Script on the context menu in the script window).

However, when I do this, the debugger halts in the guts of the class loader, and when I resume it produces this exception:

Exception in thread "main" java.lang.NoClassDefFoundError: 3/5/1/plugins/org/codehaus/groovy_1/7/0/xx-20091028-2000-e35/conf/groovy-starter/conf
Caused by: java.lang.ClassNotFoundException: 3.5.1.plugins.org.codehaus.groovy_1.7.0.xx-20091028-2000-e35.conf.groovy-starter.conf
       at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:319)
       at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:254)
       at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:399)