tomcat起步一段时间，运行程序出错,Could not roll back JPA transaction

tomcat启动一段时间，运行程序出错,Could not roll back JPA transaction
程序放在tomcat，启动tomcat，运行没问题，但是过一段时间，再运行这个程序，就报错了。
异常：org.springframework.transaction.TransactionSystemException: Could not roll back
JPA transaction; nested exception is javax.persistence.PersistenceException: une
xpected error when rollbacking


框架：struts2+jpa+spring2.5

在网上查资料，说连接mysql会出现这样的情况，我连的informix，我想是不是和mysql有同样的错误。

以为是连接池小了，改了连接池，还是一样报错。

下面我贴一下我的配置文件：

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd 
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">
	<context:annotation-config />
	<!-- *** FOLLOWING CONFIGURATION  IS BASIC LINE,DON NOT CHANGE ***-->

	<!-- BeanPostProcessor that processes PersistenceUnit  and PersistenceContext annotations -->
	<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

<bean id="entityManagerFactory"
		class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
		<property name="persistenceUnitName" value="dzInter" />
		<property name="jpaVendorAdapter">
			<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
				<property name="showSql" value="true"></property>
				<property name="database" value="INFORMIX"></property>
				<property name="generateDdl" value="true"></property>
				<property name="databasePlatform" value="org.hibernate.dialect.InformixDialect"></property>
			</bean>
		</property>
	</bean>
	<bean id="transactionManager"
		class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory"
			ref="entityManagerFactory" />
	</bean>
	<tx:annotation-driven  transaction-manager="transactionManager" /></beans>

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
    http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">
    
	<persistence-unit name="dzInter" transaction-type="RESOURCE_LOCAL">
	<provider>org.hibernate.ejb.HibernatePersistence</provider>
  		<properties>
  		<property name="hibernate.show_sql" value="true" />
  			<property name="hibernate.format_sql" value="true" />