JCRStoreProvider exception raised at page 7 of config wizard : user guest not found

2008-12-03 08:09:07,890: WARN [org.apache.jackrabbit.core.observation.ObservationDispatcher] - EventConsumer threw exception: java.lang.NullPointerException
2008-12-03 08:09:07,921: ERROR [org.jahia.services.content.JCRStoreProvider] - Repository error
javax.jcr.LoginException: User guest not found
at org.jahia.services.content.impl.jahia.RepositoryImpl.login(RepositoryImpl.java:71)
at org.jahia.services.content.impl.jahia.RepositoryImpl.login(RepositoryImpl.java:84)
at org.jahia.services.content.JCRStoreProvider.getThreadSession(JCRStoreProvider.java:377)
at org.jahia.services.content.JCRStoreProvider.getFileNodeWrapper(JCRStoreProvider.java:433)
at org.jahia.services.content.JCRNodeWrapper.getChildren(JCRNodeWrapper.java:455)
at org.jahia.services.content.CacheListener.flushNodeRefs(CacheListener.java:132)
at org.jahia.services.content.CacheListener.onEvent(CacheListener.java:94)
at org.apache.jackrabbit.core.observation.EventConsumer.consumeEvents(EventConsumer.java:244)
at org.apache.jackrabbit.core.observation.ObservationDispatcher.run(ObservationDispatcher.java:145)
at java.lang.Thread.run(Thread.java:595)
2008-12-03 08:09:07,921: ERROR [org.jahia.services.content.CacheListener] -
java.lang.NullPointerException
at org.jahia.services.content.CacheListener.flushNodeRefs(CacheListener.java:109)
at org.jahia.services.content.CacheListener.flushNodeRefs(CacheListener.java:134)
at org.jahia.services.content.CacheListener.onEvent(CacheListener.java:94)
at org.apache.jackrabbit.core.observation.EventConsumer.consumeEvents(EventConsumer.java:244)
at org.apache.jackrabbit.core.observation.ObservationDispatcher.run(ObservationDispatcher.java:145)
at java.lang.Thread.run(Thread.java:595)
2008-12-03 08:09:07,921: WARN [org.apache.jackrabbit.core.observation.ObservationDispatcher] - EventConsumer threw exception: java.lang.NullPointerException