tomcat的棘手问题，用户的远程客户端一断开，则服务报404

今天部署服务，遇到一个棘手的问题：
我们是有一个服务，部署在tomcat上，发布都是正常的，但是用户的远程客户端一旦和服务器断开，则再访问服务，报404，后台日志为java.lang.NoClassDefFoundError，这时，我再将远程客户端连上，再访问服务，一切又正常了，并查看了一下进程，进程正常。

tomcat6、JDK1.7  系统的友帮拓，同时我们也使用tomcat7与jdk1.6尝试了，结果一样.

看后台的错误信息：
Jul 31, 2013 4:04:19 PM org.apache.catalina.loader.WebappClassLoader loadClass
INFO: Illegal access: this web application instance has been stopped already.  Could not load com.sat.iteach.web.common.dc.WordExampleDc.  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:1566)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
        at com.sat.iteach.web.common.dc.SystemCacheLister$RunThread.run(SystemCacheLister.java:53)
        at java.lang.Thread.run(Thread.java:724)

Exception in thread "Thread-2" java.lang.NoClassDefFoundError: com/sat/iteach/web/common/dc/WordExampleDc
        at com.sat.iteach.web.common.dc.SystemCacheLister$RunThread.run(SystemCacheLister.java:53)
        at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.ClassNotFoundException: com.sat.iteach.web.common.dc.WordExampleDc
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
        ... 2 more
Jul 31, 2013 5:13:40 PM org.apache.catalina.core.AprLifecycleListener init
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
Jul 31, 2013 5:13:41 PM org.apache.coyote.http11.Http11Protocol init
INFO: Initializing Coyote HTTP/1.1 on http-80
Jul 31, 2013 5:13:41 PM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 1211 ms tomcat 友帮拓服务器 --------------------编程问答-------------------- 在线等啊，江湖救急。

补充：Java ,  Web 开发