NPE in UnifiedClassLoader3 -- UnifiedLoaderRepository3 is nu

[squeak]

I have had this error creep up on me a couple times here. I can't seem to get a consistent pattern to why it is happening. The only thing I do know is that once I get it, I have to reboot JBoss to make it go away.

here is the exception stack I get:

ROOT CAUSE
java.lang.NullPointerException
 at org.jboss.mx.loading.LoadMgr3.beginLoadTask(LoadMgr3.java:119)
 at org.jboss.mx.loading.UnifiedClassLoader3.loadClassImpl(UnifiedClassLoader3.java:169)
 at org.jboss.mx.loading.UnifiedClassLoader3.loadClass(UnifiedClassLoader3.java:123)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:302)
 at com.inet.tds.a.a(Unknown Source)
 at com.inet.tds.u.getObject(Unknown Source)
 at com.inet.tds.u.getDouble(Unknown Source)
 at com.inet.tds.u.getDouble(Unknown Source)
 at org.apache.ojb.broker.util.JdbcTypesHelper$T_Float.readValueFromResultSet(JdbcTypesHelper.java:770)
 at org.apache.ojb.broker.util.JdbcTypesHelper$BaseType.getObjectFromColumn(JdbcTypesHelper.java:298)
 at org.apache.ojb.broker.util.JdbcTypesHelper$BaseType.getObjectFromColumn(JdbcTypesHelper.java:277)
 at org.apache.ojb.broker.accesslayer.RowReaderDefaultImpl.readObjectArrayFrom(RowReaderDefaultImpl.java:123)
 at org.apache.ojb.broker.accesslayer.JdbcAccessImpl.materializeObject(JdbcAccessImpl.java:548)
 at org.apache.ojb.broker.core.PersistenceBrokerImpl.getDBObject(PersistenceBrokerImpl.java:1232)
 at org.apache.ojb.broker.core.PersistenceBrokerImpl.doGetObjectByIdentity(PersistenceBrokerImpl.java:1355)
 at org.apache.ojb.broker.core.QueryReferenceBroker.getReferencedObject(QueryReferenceBroker.java:467)
 at org.apache.ojb.broker.core.QueryReferenceBroker.retrieveReference(QueryReferenceBroker.java:347)
 at org.apache.ojb.broker.core.QueryReferenceBroker.retrieveReferences(QueryReferenceBroker.java:389)
 at org.apache.ojb.broker.accesslayer.RsIterator.getObjectFromResultSet(RsIterator.java:470)
 at org.apache.ojb.broker.accesslayer.RsIterator.next(RsIterator.java:265)
 at org.osn.persistence.PersistenceSessionPBImpl.executeCollectionQuery(PersistenceSessionPBImpl.java:597)
 at org.osn.persistence.PersistenceSessionPBImpl.findCollectionByCriteria(PersistenceSessionPBImpl.java:534)
 at org.osn.persistence.PersistenceSessionPBImpl.findCollectionByCriteria(PersistenceSessionPBImpl.java:508)
 at org.osn.ejb.PersistenceServiceBean.findCollectionByCriteria(PersistenceServiceBean.java:156)
 at sun.reflect.GeneratedMethodAccessor57.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:324)
 at org.jboss.ejb.StatelessSessionContainer$ContainerInterceptor.invoke(StatelessSessionContainer.java:683)
 at org.jboss.resource.connectionmanager.CachedConnectionInterceptor.invoke(CachedConnectionInterceptor.java:185)
 at org.jboss.ejb.plugins.StatelessSessionInstanceInterceptor.invoke(StatelessSessionInstanceInterceptor.java:72)

For some reason, the UnifiedLoaderRepository3 that is passed into beginLoadTask has become null.

Any thoughts on why this may be?