After I deployed some Beans (Entity+Session), then call a statefull sessoin bean remotely and then some time of inactivity (5-10 min.) JBoss issues the following error message

Exception in thread "Timer-5"
java.lang.NoClassDefFoundError: javax/xml/rpc/handler/
at java.lang.Class.getDeclaredMethods0(Native Meth
at java.lang.Class.privateGetDeclaredMethods(Class
at java.lang.Class.getDeclaredMethod(Class.java:19
at java.io.ObjectStreamClass.getInheritableMethod(
at java.io.ObjectStreamClass.access$2100(ObjectStr
at java.io.ObjectStreamClass$2.run(ObjectStreamCla
at java.security.AccessController.doPrivileged(Nat
at java.io.ObjectStreamClass.<init>(ObjectStreamCl
at java.io.ObjectStreamClass.lookup(ObjectStreamCl
at java.io.ObjectOutputStream.writeObject0(ObjectO
at java.io.ObjectOutputStream.writeObject(ObjectOu
at org.jboss.ejb3.cache.simple.StatefulSessionFile
at org.jboss.ejb3.cache.simple.SimpleStatefulCache
at org.jboss.ejb3.cache.simple.SimpleStatefulCache
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)

There is no error message during deployment, all EJBs seem to work correct, all components are serializable.
Futher deployments of the same application do not work anymore until JBoss is restarted.