TCP/IP stops blocking... Help pls...

I have a problem when I send a block of data over the page limit, the problem is the blocking somehow doesnt work anymore even when i explicitly use ioctlsocket to turn it on, I am not sure why it only does this after a large buffer is sent and recieved... I have them both in a loop to make sure the data is all sent and all recieved, that part works fine as i have steped through it all... its just that the server goes and checks to see if it can send or recieve and does it even though it should be blocked until the client sends...

Any help on the subject would be most appreciated.
thanks

os/api etc?

example code?

////////////////// --- server side ---- ////////////////////////

Code:

if( xnet.HasValidConnection() )
{
     if( xnet.IsReadAvailable() )
     {
          xnet.RecieveMsg( buff );
          if( xnet.IsWriteAvailable() )
	ServerHandleMessage( &xnet ); 
     }
}


//////////////////  ---   client side  ---- ////////////////////////
if( xnet.IsWriteAvailable() )
{
     xnet.xmsg->buffer_size = 0;
     xnet.SendMsg( GETVIDEOBUFFER, 0 );
}

if( xnet.IsReadAvailable() )
{
    xnet.RecieveMsg( xscr.mini_pixel_buffer );
    xnet.ClientHandleMsg();
}

/////////////////functions


bool IsReadAvailable()
{
		 
fd_set read_able;
int can_read = 0;
read_able.fd_count = 0;
FD_SET( client_sock, &read_able);

can_read = select( 0, &read_able, 0, 0, 0 );
if( can_read == 1 )
     return true;
else
     return false;
}

bool IsWriteAvailable()
{
fd_set write_able;
int can_write = 0;
write_able.fd_count = 0;
FD_SET( client_sock, &write_able);

can_write = select( 0, 0, &write_able, 0, 0 );
if( can_write == 1 )
     return true;
else
     return false;
}

bool SendMsg( UINT xmsg_num, void *buffer )
{
int recieved = 0;

xmsg->xmsg_num = xmsg_num;
xmsg->validity_id = VALID_MSG;

send( client_sock, (char*)xmsg, sizeof( XMSG ), 0 );
	
do
{
recieved += sendto( client_sock, (char*)buffer + recieved, xmsg->buffer_size -                                 recieved, 0, 0, 0 );
int err = WSAGetLastError();
if( err == WSAENOTCONN )
     has_connection = 0;
		
}
while( recieved < xmsg->buffer_size );
}



bool RecieveMsg( void *buffer )
{

int recieved = 0;

recv( client_sock, (char*)xmsg, sizeof( XMSG ), 0 );
if( xmsg->validity_id != VALID_MSG)
     return false;

do
{
recieved += recvfrom( client_sock, (char*)buffer + recieved, xmsg->buffer_size -                                    recieved, 0, 0, 0 ); 
int err = WSAGetLastError();
if( err == WSAENOTCONN )
     has_connection = 0;

}
while( recieved < xmsg->buffer_size );

return true;
}



void ServerHandleMessage()
{
msg->buffer_size = 400 * 320 - 1;
net_class->SendMsg( SENTVIDEOBUFFER, xscr.buffer );
}

void ClientHandleMessage()
{
//dostuff
}

thanks

Visual c++ 2005
Windows XP
Windsock 2.0

please make it compilable and indent your code.