Thank you .
In case you need, i'm posting  my configuration and the stack-trace .
Hibernate 2.2.3 Final
Spring 3.2.2. RELEASE
Activiti 5.13 
springDataJpa 1.4.1.RELEASE.
My entityManager configuration from root-context.xml :
<code>
   <context:annotation-config />
   
   <bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
      <property name="jndiName" value="java:/comp/env/jdbc/DefaultDB" />
   </bean>
   <bean id="multiTenantIdentifierResolver" class="it.sydema.laweb.utils.MultiTenantIdentifierResolver">
      <property name="defaultTenant" value="default" />
      <property name="tenants">
         <map>
            <entry key="default" value="DefaultDB" />
            <entry key="alternative" value="AlternativeDB" />
         </map>
      </property>
   </bean>
   
   <bean id="entityManagerFactory"
      class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
      <property name="jpaVendorAdapter">
         <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
      </property>
      <property name="jpaPropertyMap">
         <map>
            <entry key="hibernate.show_sql" value="true" />
            <entry key="hibernate.use_sql_comments" value="true" />
            <entry key="hibernate.format_sql" value="true" />
            <entry key="hibernate.dialect" value="it.sydema.laweb.utils.SQLServerDialectEx" />
            <entry key="hibernate.connection.datasource" value="java:/comp/env/jdbc/DefaultDB" />
            <entry key="hibernate.multiTenancy" value="DATABASE" />
            <entry key="hibernate.tenant_identifier_resolver">
               <ref bean="multiTenantIdentifierResolver" />
            </entry>
            <entry key="org.hibernate.envers.store_data_at_delete" value="true" />
            <entry key="hibernate.cache.region.factory_class"
               value="org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory" />
            <entry key="hibernate.cache.use_second_level_cache" value="true" />
            <entry key="hibernate.cache.use_query_cache" value="true" />
            <entry key="net.sf.ehcache.configurationResourceName" value="/ehcache.xml" />
      </map>
      </property>
      <property name="dataSource" ref="dataSource" />
   </bean>
   <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
   </bean>
   <tx:annotation-driven transaction-manager="transactionManager" />
</code>
Activiti configuration from activiti-context.xml
<code>
<bean id="processEngineConfiguration" class="org.activiti.spring.SpringProcessEngineConfiguration"> 
   
   <property name="databaseType" value="mssql" />  
     <property name="dataSource" ref="dataSource" />
     <property name="transactionManager" ref="transactionManager" />
     
     <property name="databaseSchemaUpdate" value="false" />
     <property name="jobExecutorActivate" value="false" />
     <property name="jpaEntityManagerFactory" ref="entityManagerFactory" />
    <property name="jpaHandleTransaction" value="true" />
    <property name="jpaCloseEntityManager" value="true" />
    
    <property name="mailServerHost" value="localhost" />
    <property name="mailServerPort" value="5025" />
    <property name="customFormTypes">
      <list>
        <bean class="org.activiti.explorer.form.UserFormType"/>
        <bean class="org.activiti.explorer.form.ProcessDefinitionFormType"/> 
        <bean class="org.activiti.explorer.form.MonthFormType"/>   
        <bean class="it.sydema.laweb.activiti.FormTypeAmount" />
        <bean class="it.sydema.laweb.activiti.FormTypeDecimal" />
        <bean class="it.sydema.laweb.activiti.FormTypeInteger"/>
        <bean class="it.sydema.laweb.activiti.FormTypeText"/>
        <bean class="it.sydema.laweb.activiti.FormTypeEntity"/>
        <bean class="it.sydema.laweb.activiti.FormTypeValidationRule"/>
      </list>
    </property>
    <!– property for custom user and groups –>  
     <property name="customSessionFactories">
        <list>
        <bean class="it.sydema.laweb.activiti.CustomUserManagerFactory">
         <constructor-arg ref="MyConnectionParams" />
      </bean>               
      <bean class="it.sydema.laweb.activiti.CustomGroupManagerFactory">
             <constructor-arg ref="MyConnectionParams" />               
       </bean>
      </list>
   </property>
</bean>        
<bean id="processEngine" class="org.activiti.spring.ProcessEngineFactoryBean" destroy-method="destroy">
   <property name="processEngineConfiguration" ref="processEngineConfiguration" />
</bean>
</code>
error stacktrace : 
<code>
nov 19, 2013 10:33:09 AM org.apache.catalina.core.StandardContext listenerStart
Grave: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'activitiController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.activiti.engine.ProcessEngine it.sydema.laweb.controllers.ActivitiController.processEngine; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine': FactoryBean threw exception on object creation; nested exception is org.springframework.orm.hibernate3.HibernateSystemException: commit failed; nested exception is org.hibernate.TransactionException: commit failed
   at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:288)
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1116)
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
   at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
   at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
   at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
   at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
   at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:628)
   at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
   at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
   at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389)
   at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294)
   at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
   at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4791)
   at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5285)
   at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
   at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
   at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
   at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
   at java.util.concurrent.FutureTask.run(Unknown Source)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
   at java.lang.Thread.run(Unknown Source)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.activiti.engine.ProcessEngine it.sydema.laweb.controllers.ActivitiController.processEngine; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine': FactoryBean threw exception on object creation; nested exception is org.springframework.orm.hibernate3.HibernateSystemException: commit failed; nested exception is org.hibernate.TransactionException: commit failed
   at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:514)
   at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
   at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:285)
   … 23 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine': FactoryBean threw exception on object creation; nested exception is org.springframework.orm.hibernate3.HibernateSystemException: commit failed; nested exception is org.hibernate.TransactionException: commit failed
   at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:149)
   at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:102)
   at org.springframework.beans.factory.support.AbstractBeanFactory.getObjectForBeanInstance(AbstractBeanFactory.java:1454)
   at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:306)
   at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
   at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:912)
   at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:855)
   at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:770)
   at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486)
   … 25 more
Caused by: org.springframework.orm.hibernate3.HibernateSystemException: commit failed; nested exception is org.hibernate.TransactionException: commit failed
   at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:690)
   at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:104)
   at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:516)
   at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:755)
   at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:724)
   at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:148)
   at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:40)
   at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:31)
   at org.activiti.engine.impl.ProcessEngineImpl.<init>(ProcessEngineImpl.java:76)
   at org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl.buildProcessEngine(ProcessEngineConfigurationImpl.java:365)
   at org.activiti.spring.SpringProcessEngineConfiguration.buildProcessEngine(SpringProcessEngineConfiguration.java:64)
   at org.activiti.spring.ProcessEngineFactoryBean.getObject(ProcessEngineFactoryBean.java:56)
   at org.activiti.spring.ProcessEngineFactoryBean.getObject(ProcessEngineFactoryBean.java:32)
   at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:142)
   … 33 more
Caused by: org.hibernate.TransactionException: commit failed
   at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:185)
   at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:75)
   at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:512)
   … 44 more
Caused by: org.hibernate.TransactionException: unable to commit against JDBC connection
   at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doCommit(JdbcTransaction.java:116)
   at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:178)
   … 46 more
Caused by: java.sql.SQLException: Connection is closed.
   at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.checkOpen(PoolingDataSource.java:185)
   at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.commit(PoolingDataSource.java:210)
   at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doCommit(JdbcTransaction.java:112)
   … 47 more
</code>
I've already tried Hibernate 4.2.7.SP1 without any changes.
if you need some more info,  just ask.