Socket EnableBroadcast MulticastLoopback SocketException 10042

[oferns]

Hi,
apologies for the cluncky title....

Using WinXpSP2 & VS2005 Express editions.....

I am writing an asynchronous socket client and I am getting a
SocketException error on creating the socket:

+ EnableBroadcast 'this.client.EnableBroadcast' threw an exception of
type 'System.Net.Sockets.SocketException' bool
{System.Net.Sockets.SocketException}

+ MulticastLoopback 'this.client.MulticastLoopback' threw an exception
of type 'System.Net.Sockets.SocketException' bool
{System.Net.Sockets.SocketException}


The error is...

- base {"An unknown, invalid, or unsupported option or level was
specified in a getsockopt or setsockopt
call"} System.ComponentModel.Win32Exception
{System.Net.Sockets.SocketException}

ErrorCode 10042 int

This does not raise an exception when I create the socket, nor when I
try to send data through the socket. This appears to work. However,
when I begin the async recieve call, my program hangs waiting for a
recieve callback...I only found this by putting a watch on the socket.
I can raise the error by attempting to call set either property...

Has anyone got any knowledge of what might be happening here? I don't
have the option to try a different machine right now....

I tried turning the firewall etc off...
Thanks,
Oliver