when changing job configurations Hudson throws a lot HTTP 500 errors although going back to the job configuration page all the relevant changes are preserved.

see an example below:
15-Jun-2010 10:45:16 org.apache.catalina.core.ApplicationContext log
SEVERE: Error while serving http://ci.example.com:8080/hudson/view/aTab/job/testA/configSubmit
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:235)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:116)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:57)
at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:75)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:525)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:181)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:525)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:181)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:525)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:441)
at org.kohsuke.stapler.Stapler.service(Stapler.java:123)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:94)
at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:368)
at org.jvnet.hudson.plugins.monitoring.HudsonMonitoringFilter.doFilter(HudsonMonitoringFilter.java:42)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:97)
at hudson.plugins.greenballs.GreenBallFilter.doFilter(GreenBallFilter.java:51)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:97)
at hudson.plugins.audit_trail.AuditTrailFilter.doFilter(AuditTrailFilter.java:64)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:97)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:86)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:166)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.basicauth.BasicProcessingFilter.doFilter(BasicProcessingFilter.java:173)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:66)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:859)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:574)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1527)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.io.IOException: Unable to delete D:\Hudson\.hudson\jobs\testA\config.xml
at hudson.util.AtomicFileWriter.commit(AtomicFileWriter.java:109)
at hudson.XmlFile.write(XmlFile.java:166)
at hudson.model.AbstractItem.save(AbstractItem.java:220)
at hudson.model.Job.save(Job.java:167)
at hudson.model.Job.doConfigSubmit(Job.java:1053)
at hudson.model.AbstractProject.doConfigSubmit(AbstractProject.java:555)
... 66 more

I am not sure if this just an Hudson Core issue or it is linked to the Job configuration History plugin (1.5). I will disable the plugin in order to narrow down what generates the problem.

many thanks