java.lang.NullPointerException
    at org.apache.mina.io.socket.SocketIoProcessor.flush(SocketIoProcessor.java:496)
    at org.apache.mina.io.socket.SocketIoProcessor.flushSessions(SocketIoProcessor.java:402)
    at org.apache.mina.io.socket.SocketIoProcessor.access$3(SocketIoProcessor.java:377)
    at org.apache.mina.io.socket.SocketIoProcessor$Worker.run(SocketIoProcessor.java:525)

is error I'm running into and I'm unsure of the cause.  I am closing ProtocolSessions and creating new ones which may have something to do with it.  I also use the DemuxingProtocolCodecFactory to manage my protocol messages as well as their encoding and decoding.  

I cannot figure out how the session's SelectionKey is becoming null.  I am using a checkout of the 0.7 branch from earlier today.  

Thanks for any help,
Adam