When starting Hudson CI via "java -jar hudson.war --httpPort=8008" I find the following in the log file:

Mar 10, 2010 8:38:06 AM hudson.triggers.SafeTimerTask run
SEVERE: Timer task hudson.WebAppMain$2$1@214d8c01 failed
java.lang.NullPointerException
at hudson.util.XStream2$AssociatedConverterImpl.findConverter(XStream2.java:152)
at hudson.util.XStream2$AssociatedConverterImpl.canConvert(XStream2.java:198)
at com.thoughtworks.xstream.core.DefaultConverterLookup.lookupConverterForType(DefaultConverterLookup.java:63)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:60)
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:137)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:33)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:926)
at hudson.util.XStream2.unmarshal(XStream2.java:76)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:912)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:864)
at hudson.plugins.filesystem_scm.ChangelogSet$XMLSerializer.parse(ChangelogSet.java:92)
at hudson.plugins.filesystem_scm.ChangelogSet$XMLSerializer.parse(ChangelogSet.java:72)
at hudson.model.AbstractBuild.calcChangeSet(AbstractBuild.java:652)
at hudson.model.AbstractBuild.getChangeSet(AbstractBuild.java:627)
at hudson.model.AbstractBuild.hasParticipant(AbstractBuild.java:315)
at hudson.model.User.getBuilds(User.java:366)
at hudson.WebAppMain$2$1.doRun(WebAppMain.java:231)
at hudson.triggers.SafeTimerTask.run(SafeTimerTask.java:54)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)