Class not found errors from inside hudson in builds?

[Benson Margulies <bi...@gmail.com>]

[HUDSON] Archiving
/home/hudson/hudson-slave/workspace/CXF-Trunk-JDK16/trunk/common/xsd/pom.xml
to /export/home/hudson/hudson/jobs/CXF-Trunk-JDK16/modules/org.apache.cxf$cxf-common-xsd/builds/2009-07-06_01-51-39/archive/org.apache.cxf/cxf-common-xsd/2.3.0-SNAPSHOT/pom.xml
Jul 6, 2009 1:52:53 AM hudson.remoting.Channel$ReaderThread run
SEVERE: Unable to read a command
java.lang.ClassNotFoundException: hudson.remoting.ProxyOutputStream$Unexport
	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
	at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195)
	at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255)
	at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:274)
	at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:274)
	at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:247)
	at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:604)
	at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1575)
	at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1732)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
	at hudson.remoting.Channel$ReaderThread.run(Channel.java:637)