Hello

I have a multi-tier application which uses tcp/ip for communication between
tier.
Sometimes during the startup of the server I get the following exception
(the first line was added by my application):

Exception in method HandeOnError: System.Exception: Error sending
string --->
System.ArgumentNullException: Value cannot be null.
Parameter name: buffer
  at System.Net.Sockets.NetworkStream.BeginWrite(Byte[] buffer, Int32
offset, Int32 size, AsyncCallback callback, Object state)
  at AdsTCPServer.TAdsConnection.Send(String Data)
  --- End of inner exception stack trace ---
  at AdsTCPServer.TAdsConnection.Send(String Data)

As you'll be able to see in the following code, I check every parameter the
BeginWrite method receives (in the "catch" clause), and according to the
"Error sending string" header, all of the parameters passed the check:

public void Send(string Data)
{
if (IsOpen())
{
 try
 {
  if (m_oSocket != null)
  {
   Data+= m_strWriteTerminator;
   m_arrWriteBuffer = Encoding.ASCII.GetBytes (Data);

   NetworkStream netstream = m_oSocket.GetStream();
   try
    {
    if (netstream != null)
    {
     lock(netstream)
     {
      if (netstream.CanWrite)
      {
       netstream.BeginWrite(m_arrWriteBuffer,0, Data.Length,
m_SendCallback,netstream);
      }
     }
    }
   }
   catch (Exception E)
   {
    Exception myException;
    if (m_SendCallback == null)
     myException = new Exception("Error sending string: m_SendCallback is
null", E);
    if (m_arrWriteBuffer == null)
     myException = new Exception("Error sending string: m_arrWriteBuffer is
null", E);
    else
     if (m_arrWriteBuffer.Length == 0)
      myException = new Exception("Error sending string: m_arrWriteBuffer
is 0 length", E);
    if (Data == null)
     myException = new Exception("Error sending string: Data is null", E);
    if (netstream == null)
     myException = new Exception("Error sending string: netstream is null",
E);
    if (Data == "")
     myException = new Exception("Error sending string: Data is empty", E);
    else
     myException = new Exception("Error sending string", E);
    throw myException;
   }
   netstream        = null;
   m_arrWriteBuffer = null;
  }
 }
 catch (Exception E)
 {
  if (IsSocketDown(E.ToString()))
   DoOnDisconnect();
  else
   DoOnError(E);
 }
 GC.Collect();
}
}

Any idea what causes this exception?