>I know you're thinking, "Um, duh!" but...
>
>I'm opening a port for listening by using the following:
>
>

>.tcpServer.Object.LocalPort = m.Port
>.tcpServer.Object.Listen
>

>
>That port remains listening until... When?
>
>UPDATE: The real issue is that once something is sent from a 3rd-party app to the port, it doesn't seem to be able to send again.
>
>UPDATE2: This page had some possibly relevent, but I'm not sure if it really is: http://www.netbook.cs.purdue.edu/othrpags/qanda148.htm
>
>Primarily:
>
>

>A: That's unlikely. It's more likely that the application on B does not close (or shutdown) the socket after receiving the end-of-file. If your hypothesis was correct, side B would remain in the LAST ACK state instead.
>
>There is one other possibility: TCP has been implemented incorrectly. It could be that when a process is killed, TCP does not shutdown the control block correctly, meaning that it will fail to send an error message (RESET)
>

>
>Do I need to have my listening service to close the socket after receiving the information? How do I know what the information being sent is done?

Do you have a firewall on the server (listener)? Some are adaptive and may add ports to the blocked list unexpectedly, on the fly.