Spring and Hibernate suddenly set the transaction to readonly

We have an application running on JBoss 4.2.3, using Spring 2.5.2 and Hibernate 3.2.6.ga. This is running on Linux JEE01 2.6.16.60-0.54.5-smp, using its own user. Writing to a Oracle 10G database on another machine.

We're using a standard view -> service -> dao layering. Where each dao is annotated with @Repository.

This is all running 24/7 without many problems, but every several days and sometimes a couple of times in one day the whole system goes into a bad state where nothing can be written to the database anymore. These stacktraces appear in the logs:

org.springframework.dao.InvalidDataAccessApiUsageException: Write operations are not
      allowed in read-only mode (FlushMode.NEVER/MANUAL): 
Turn your Session into FlushMode.COMMIT/AUTO or remove 'readOnly' marker from transaction
      definition.

We scanned the complete system, and there is one place in the system where the flushmode is temporarely set to MANUAL after which a finally block set its back to its original value. This is because we do not want to flush the state to the database before this query runs. So we can't change this very easily. The normal FlushMode is set to AUTO and on several places we temporarily set it to COMMIT and switching it back to the default again.

Only a server restart restores the system back to working order.

The question is: why does the system set all transactions to readonly/manual flush mode? I googled this but could not find a solution.

This is our spring and hibernate configuration (only relevants part showing):

     <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
  <property name="dataSource">
   <ref bean="datasourceName" />
  </property>
  <property name="configLocation">
   <value>classpath:hibernate.cfg.xml</value>
  </property>
 </bean>

 <bean id="hibernateInterceptor"
  class="org.springframework.orm.hibernate3.HibernateInterceptor">
  <property name="sessionFactory" ref="sessionFactory" />
 </bean>

 <tx:annotation-driven transaction-manager="txManager" /> 

 <tx:advice id="txAdvice" transaction-manager="txManager" >
  <!-- the transactional semantics... -->
  <tx:attributes >
   <!-- all methods starting with 'get' are read-only -->
   <tx:method name="approve*" read-only="false"
    propagation="REQUIRED" rollback-for="java.lang.Exception" />
   <tx:method name="update*" read-only="false"   
    propagation="REQUIRED" rollback-for="java.lang.Exception"/>
   <tx:method name="save*" read-only="false"
    propagation="REQUIRED" rollback-for="java.lang.Exception"/>
            <tx:method name="delete*" read-only="false"
    propagation="REQUIRED" rollback-for="java.lang.Exception" />
   <!-- other methods use the default transaction settings (see below) -->
   <tx:method name="*" read-only="true" propagation="REQUIRED" />
  </tx:attributes>
 </tx:advice>

 <aop:config>
  <aop:pointcut id="serviceMethods"
   expression="execution(* com.myapplication.service.*.*(..))"  />
  <aop:advisor advice-ref="txAdvice" 
   pointcut-ref="serviceMethods" />
 </aop:config>

 <bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager" >
  <property name="sessionFactory" ref="sessionFactory"  />
 </bean>

-- end of spring config --

-- hibernate configuation --
<hibernate-configuration>
    <session-factory name="">
        <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
        <property name="show_sql">false</property>
        <property name="use_outer_join">false</property>
        <property name="hibernate.cache.use_query_cache">true</property>
        <property name="hibernate.cache.use_second_level_cache">true</property>
        <property name="cache.provider_class">org.hibernate.cache.EhCacheProvider</property>
        <property name="hibernate.connection.SetBigStringTryClob">true</property>
        <property name="hibernate.jdbc.batch_size">0</property>
    </session-factory>
    <mapping ----/>
</hibernate-configuration>

This is the stacktrace:

org.springframework.dao.InvalidDataAccessApiUsageException: Write operations are not allowed in read-only mode (FlushMode.NEVER/MANUAL): Turn your Session into FlushMode.COMMIT/AUTO or remove 'readOnly' marker from transaction definition.
at org.springframework.orm.hibernate3.HibernateTemplate.checkWriteOperationAllowed(HibernateTemplate.java:1137)
at org.springframework.orm.hibernate3.HibernateTemplate$16.doInHibernate(HibernateTemplate.java:701)
at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:374)
at org.springframework.orm.hibernate3.HibernateTemplate.saveOrUpdate(HibernateTemplate.java:699)
at nl.company.myapp.dao.impl.GenericDAOImpl.save(GenericDAOImpl.java:94)
at nl.company.myapp.dao.impl.CallDAOImpl.save(CallDAOImpl.java:266)
at nl.company.myapp.dao.impl.CallDAOImpl.save(CallDAOImpl.java:47)
at nl.company.myapp.service.impl.CallServiceImpl.saveCall(CallServiceImpl.java:98)
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:592)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:310)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at $Proxy142.saveCall(Unknown Source)
at nl.company.myapp.view.bean.call.CallDetailBean.doSave(CallDetailBean.java:319)
at nl.company.myapp.view.bean.EditModeAwareBean.save(EditModeAwareBean.java:151)
at sun.reflect.GeneratedMethodAccessor472.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:592)
at org.apache.el.parser.AstValue.invoke(AstValue.java:131)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
at com.sun.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:68)
at org.apache.myfaces.trinidad.component.MethodExpressionMethodBinding.invoke(MethodExpressionMethodBinding.java:46)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at org.apache.myfaces.trinidad.component.UIXCommand.broadcast(UIXCommand.java:190)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:458)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:763)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at nl.company.myapp.view.audit.AuditFilter.doFilter(AuditFilter.java:88)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._invokeDoFilter(TrinidadFilterImpl.java:238)
at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._doFilterImpl(TrinidadFilterImpl.java:195)
at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl.doFilter(TrinidadFilterImpl.java:138)
at org.apache.myfaces.trinidad.webapp.TrinidadFilter.doFilter(TrinidadFilter.java:92)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:265)
at org.acegisecurity.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:107)
at org.acegisecurity.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:72)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:124)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.wrapper.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:81)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.ui.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:149)
at org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:98)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:182)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:432)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:437)
at org.apache.coyote.ajp.AjpProtocol$AjpConnectionHandler.process(AjpProtocol.java:366)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
at java.lang.Thread.run(Thread.java:595)

This all works fine