This occurs only on Windows 2000 in "receive" method of DatagramSocket class.
When client socket comes into recieve method without any server
socket, we get an unexpected java.net.SocketException like this:

[thread MyThread]:exception occurred java.net.SocketException: socket closed
java.net.SocketException: socket closed
        at java.net.PlainDatagramSocketImpl.receive(Native Method)
        at java.net.DatagramSocket.receive(DatagramSocket.java:392)
        at MyThread.run(MyThread.java:15)

It doesn't happen on Windows NT, Solaris. And, if you start server socket
prior to client, you will not get any exception.

I got this exception with JDK1.1.8, JDK1.2, and JDK1.3.

To reproduce this problem with sample code, you should do as follows;
- compile following 3 java files attached
- Type "java DatagramClient" in prompt.

[Note] You need not DatagramServer.java to reproduce it.
I'm attaching it only for reference.