求大神帮忙看下这个错误是什么

八月 07, 2013 9:50:29 上午 org.apache.catalina.loader.WebappClassLoader loadClass
INFO: Illegal access: this web application instance has been stopped already.  Could not load org.apache.mina.core.session.SessionState.  The eventual following stack trace is caused by an error thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access, and has no functional impact.
java.lang.IllegalStateException
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1600)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
at org.apache.mina.transport.socket.nio.NioProcessor.getState(NioProcessor.java:194)
at org.apache.mina.transport.socket.nio.NioProcessor.getState(NioProcessor.java:44)
at org.apache.mina.core.polling.AbstractPollingIoProcessor.removeSessions(AbstractPollingIoProcessor.java:554)
at org.apache.mina.core.polling.AbstractPollingIoProcessor.access$800(AbstractPollingIoProcessor.java:67)
at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.run(AbstractPollingIoProcessor.java:1132)
at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:64)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)Exception in thread "pool-1-thread-1" java.lang.NoClassDefFoundError: org/apache/mina/core/session/SessionState
at org.apache.mina.transport.socket.nio.NioProcessor.getState(NioProcessor.java:194)
at org.apache.mina.transport.socket.nio.NioProcessor.getState(NioProcessor.java:44)
at org.apache.mina.core.polling.AbstractPollingIoProcessor.removeSessions(AbstractPollingIoProcessor.java:554)
at org.apache.mina.core.polling.AbstractPollingIoProcessor.access$800(AbstractPollingIoProcessor.java:67)
at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.run(AbstractPollingIoProcessor.java:1132)
at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:64)
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: java.lang.ClassNotFoundException: org.apache.mina.core.session.SessionState
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1714)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
... 9 moreAndroid服务器mina异常