Hmm well I can't make out the error from that description but just double check your code to see if it follow a similar schematics to this.
Server:
1:Create socket (Set it up obviously)
2:Bind socket to a local port, in your case it's 127.0.0.1 port 5000 which is a localhost address.
3:Put that binded socket into listening mode.(Once a socket is in listening mode you can reuse it to accept multiple connections given that you don't overwritte the listening socket variables value with something else)
4: You could rather go two easy ways. Accept only one connection and have a P2P connection going on or have it be dynamic in the sense that you have the main thread always Accepting new connections to new sockets. Then you have a separate thread handling sending and receiving messages(The operating system should handle synchronization in this case).
5: Which ever way you go it's almost the same. Accept a connection into a separate socket than the one that's listening. Send some data to client. And have the client receive it. Visa versa.
Client:
1:Create socket (Set it up obviously)
2:Bind socket to a local port, 127.0.0.1 but with a different port that's not 5000 since your server will be using that port and you'll get an error if you try to bind to an already binded port
3: Settup the correct parameters(IP:127.0.0.1, Port:5000) for the socket you want to connect to.
4:Attempt to connect to the server and recv data or send.
Ps. Remember to give your processor some breathing room for now. So (I think it's the same for C# as in c++) use the function Sleep at the end of the loops that send and recv data just for now.
BONUS: Look what I found on google about borderless windows

/ the answer to your prayers
This is the best one i've found on getting rid of boders... Given it's c++ but it remains.
These use WPF which is a .NET thing...
http://stackoverflow.com/questions/6935557/in-wpf-how-do-i-create-a-dialog-like-window-i-e-gray-background-with-no-borde
http://weblogs.asp.net/psheriff/archive/2009/10/12/creating-border-less-windows-in-wpf.aspx