Check the INFORMIX.INI file. The protocol name that is specified in the [INET_CONNECTION] section should match the protocol name that is specified in the [INET_PROTOCOL] section. The protocol name must define the correct .DLL module for that protocol. If you are using an IPX/SPX protocol, then ipx=INETIPX.DLL. If you are using a Windows Sockets 1.1-compliant TCP/IP protocol, then tcpip=INETWSOK.DLL.