Problems with COM ports

[danweb]

Brief Description
I am trying to code a piece of software that will load a text file from a directory, then send that data out to a com port.
The Problem
I get an error on the machine that points to the BAUD rate being incorrect, yet I am confident that the BAUD is set correctly.

Details
I am sending the data via a Windows XP machine, running my software. It is connected to COM1. The PC is them directly connected via an RS232 cable to a Bosch CNC control (Model CC220).
When I send my Data I get the following error;
"Overflow Read Field" The error code it gives me is 2662.
When I check the error codes, it tells me that Error 2662 is a "Loss of read-in data."
It suggests that I check my BAUD rate, and it also points to problems with the interface or with the data iput device (the PC).
I can rule out all but the BAUD rate, as I get the error wether I use my Laptop or the PC I have installed specifically for connecting to the CNC. I can also rule out interface errors, because we can communicate fine with the PC, using a DOS command to copy the file straight to the com port.

The Code

    Private Sub sendToLaser3()
        Try
            Using comPort As IO.Ports.SerialPort = My.Computer.Ports.OpenSerialPort(com)
                If OpenFileDialog1.ShowDialog() = DialogResult.OK Then
                    Dim fileReader As String
                    fileReader = My.Computer.FileSystem.ReadAllText(OpenFileDialog1.FileName)
                    comPort.DtrEnable = True
                    comPort.RtsEnable = True
                    comPort.Handshake = Ports.Handshake.None
                    comPort.BaudRate = 9600
                    comPort.Parity = Ports.Parity.Even
                    comPort.StopBits = Ports.StopBits.One
                    comPort.DataBits = 7
                    ' writes the fileBytes data to the comPort
                    comPort.WriteLine(fileReader)
                    comPort.Close()
                End If
            End Using
        Catch ex As Exception
            MsgBox(com & " not found. Please try other com port(s)")
        End Try
        lblSending.Hide()
    End Sub

I know this is quite specialised, but any help or ideas would be great,

Fingers Crossed

Dan