Tom, to update, i added Winsock 6 ActiveX control (mswinsck.ocx) to
use in VB.NET to accomplish a basic chat operation on the same
machine(127.0.0.1) and here is an exception that Winsock 6 throws when
sending text string (data) from client to server:
"Exception from HRESULT: 0x800A9C46"

Full client code:

And it fails at:
"tcpClient.SendData(CStr(TextBox2.Text.ToString))" and unusing "CStr"
also made no difference.

Public Class Form1

   Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
       Try
           tcpClient.RemotePort = 1001
       Catch ex As Exception
           MsgBox(ex.Message)
       End Try
   End Sub

   Private Sub Button2_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles Button2.Click
       Try
           tcpClient.RemoteHost = Trim(TextBox3.Text)
           tcpClient.Connect()
       Catch ex As Exception
           MsgBox(ex.Message)
       End Try
   End Sub

   Private Sub Button3_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles Button3.Click
       tcpClient.Close()
   End Sub

   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles Button1.Click
       If Not TextBox2.Text = "" Then
           tcpClient.SendData(CStr(TextBox2.Text.ToString))
       End If
   End Sub

   Private Sub tcpClient_DataArrival(ByVal sender As System.Object,
ByVal e As AxMSWinsockLib.DMSWinsockControlEvents_DataArrivalEvent)
Handles tcpClient.DataArrival
       Dim strData As String
       tcpClient.GetData(strData)
       MsgBox(strData)

   End Sub
End Class

Is it a coding error or because Winsock 6's behaviour in VB.NET?

Thanks