Strange SocketException

Question

I'm writing a server-client software, with the client being an Applet and the server running at the webserver. As it is now it works just perfectly on most computers, actually all but one that I tried - which I find strange.
Here's a snippet of what is causing the problem:
private InputStream   in;
private Socket        socket;
try
    socket = new Socket(host, port);
    in = socket.getInputStream();
    socket.shutdownOutput();
catch(Exception e)
    e.printStackTrace();
try
    int bc = in.read(b, 0, bufferSize);
catch(SocketException se)
    se.printStackTrace();
}Quite a bit is left out, but nothing that should be able to interfer with this. As I said, this works at all computers I've tried this on, different geographical positions, different connection speeds, both UNIX and WinXP. EXCEPT one computer., when I run it the in.read(... causes the following exception:
java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(Unknown Source)
at gui.Receiver.run(ImageReceiver.java:119)
This happens at the first read. If I test the socket with socket.isConnected() right before the read it returns true. I've tried with another computer at the same connection, and that one works.
Why could that be that this particular computer resets the connection? Or why would the server reset the connection to this computer only? The configuration of the computer is:
Windows XP
Sun Java JRE 1.5_03
Norton Internet Security, with all options set to default
I've set up my own computer in, as far as I can see, the same way, but it works just fine....
Any ideas?

Answer 1

Well, the problem is not that I have a firewall that stops me.
The problem is that other people has firewalls and this is supposed to be a component on a website. Of course if a user has a hardware firewall which drops packets there is not much I can do.
However, I have two different new Socket(host, port) in the Applet, both connecting to the same host (of course the host the Applet comes from, due to Applet security restictions), but on different ports (at the server side). It seems like the other connection works, so Norton cannot block everything.
To be more specific: When the Applet starts one of the first thing it does is to connect to the host at a predefined port where the server has a ServerSocket listening, this continously listens for new users that connect. A short while later on in the protocol the client gets a message including another port number to open another connection to, this is a port specific for this user. The server has a ServerSocket listening on that port and the client connects, but when the client later on is trying to read the InputStream of that socket the Exception above occurs.
So howcome it works the first time, but not the second? The connections are made in the exact same way.