the following fails on all W2K machines i've tried it on: invoke socket, PF_INET, SOCK_DGRAM, NULL It returns with the error WSAEINVAL. Does anyone know what im doing wrong? All i try to do is create an UDP socket and the above works on Windows 95/98 and ME but not on some friends W2K machines. Does anyone have working UDP code to show me? i've tried specifying IPPROTO_UDP instead of NULL but it still doesn't work.