Unknown origin of error message


I have written a simple BBC Basic program that makes a tcp connection to
a remote host, then reads from/writes to that host. The program also
opens a COM port.

When running the program here, everything is fine (and so easy with BBC

However, someone else is now testing the program. He is running the
compiled .exe version -- he does not have BBC Basic on his machine. The
program successfully makes the tcp connection, but then, when attempting
to read from the port, an error message box pops up. The title bar says
simply "Error", and the message text says simply "Invalid channel".

I have no idea where this message came from.

As part of initialisation, the program contains these lines:
install @lib$+"SOCKLIB"

on error sys "MessageBox",@hwnd%,report$,0,0 : proccleanup : quit

This is the only mention of "Message Box" in the whole program, so I
assume this is what's producing the Error pop-up.

Is there any way of tracking down exactly what caused the error message
to appear and what it means?

Ian, G3NRW

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