请教在tomcat使用Spring+hibernate的hCacheBasedUserCache问题

[Samland]

我的项目在tomcat下使用了Spring+hibernate框架， 问什么老是出现以下错误？

信息: Starting Servlet Engine: Apache Tomcat/5.5.20
2006-12-12 9:49:06 org.apache.catalina.core.StandardHost start
信息: XML validation disabled
[javaoa] ERROR [main] ManagerBase.doLoad(411) | IOException while loading persis
ted sessions: java.io.WriteAbortedException: writing aborted; java.io.NotSeriali
zableException: org.acegisecurity.providers.dao.cache.EhCacheBasedUserCache
java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException
: org.acegisecurity.providers.dao.cache.EhCacheBasedUserCache
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1309)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:19
08)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1832)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1
719)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1305)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:19
08)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1832)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1
719)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1305)
at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1634)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1299)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:19
08)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1832)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1
719)