Sporadic javax.ejb.AccessLocalException

I'm using Glassfish 3.0.1. I sometimes get this error when attempting to call a local EJB:

[#|2010-11-10T19:17:25.014+0000|INFO|glassfish3.0.1|javax.enterprise.system.core.security|
_ThreadID=26;_ThreadName=Thread-1;|JACC Policy Provider: Failed Permission Check,
context(myApplication/myWarModule-1_0-SNAPSHOT_war_internal)- 
permission((javax.security.jacc.EJBMethodPermission MyEJB myMethod,Local,java.lang.Long))|#]

[#|2010-11-10T19:17:25.015+0000|WARNING|glassfish3.0.1|
javax.enterprise.system.container.ejb.com.sun.ejb.containers|_ThreadID=26;
_ThreadName=Thread-1;|A system exception occurred during an invocation on EJB 
M开发者_StackOverflowyEJB method public void com.example.MyEJB.myMethod(java.lang.Long)
javax.ejb.AccessLocalException: Client not authorized for this invocation.
    at com.sun.ejb.containers.BaseContainer.preInvoke(BaseContainer.java:1850)
    at com.sun.ejb.containers.EjbAsyncTask.call(EjbAsyncTask.java:95)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
    at java.util.concurrent.FutureTask.run(FutureTask.java:138)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:619)

99% of the time, everything works fine. But when it happens, then every attempt to call that EJB method results in the same error. The only way to fix it is to undeploy the application, and deploy again. Can anybody tell me what's going on?