HTTP Post error

[Klem]

I am doing HTTP post and I am receiving the following error:

System.IO.IOException: Unable to write data to the transport
connection. ---> System.Net.Sockets.SocketException: An established
connection was aborted by the software in your host machine at
System.Net.Sockets.Socket.BeginSend(Byte[] buffer, Int32 offset, Int32
size, SocketFlags socketFlags, AsyncCallback callback, Object state) at
System.Net.Sockets.NetworkStream.BeginWrite(Byte[] buffer, Int32
offset, Int32 size, AsyncCallback callback, Object state)

Does any one have an idea what is wrong. I know that firewall is open.

Thnx

Klem