error 10022 (invalid argument) calling "socket"

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C++

*** New wrinkle - Another programmer at my work has no problem with this code. However, he appears to have a different version of WS2_32.lib than I do. My WS2_32.lib seems to be an older version than what he has. I cannot find anything online regarding versions of WS2_32.lib. Does anyone have any ideas that might shed some light on this issue? ***

#include <winsock2.h>

int main(int argc, char **argv) 
{
int		ver=2, rev=2, retval;
WORD		wVersionRequested = MAKEWORD(ver,rev);
WSADATA		wsaData;
SOCKET		listen_socket;

    retval = WSAStartup(wVersionRequested,&wsaData);

// retval returns with a value of 0
// wsaData.wVersion has LOBYTE and HIBYTE = ver and rev (which are both = 2)

    listen_socket = socket(AF_INET, SOCK_STREAM, 0);

// listen_socket returns with a value of -1

    if (listen_socket == INVALID_SOCKET)
    {
        m = WSAGetLastError();
    }

// m = 10022 which is "invalid argument". 
// At this point, I am officially bewildered.
}

running on Windows 7
using Visual Studio 2008 Pro Edition
changing 3rd socket parameter from 0 to IPPROTO_TCP did not alter the outcome
This is the entire program.

Any answers, theories or wild guesses will be appreciated