I have no great regard for WZC, but it works for me (after learning its foibles).
I would recommend removing the TCP/IP stack on the problem machine(s), along with the NIC drivers and then re-installing the drivers followed by TCP/IP.
At least, given what I understand from your situation, that is what I would do myself.
I would also double check that there is no other wifi configuration utility butting in uninvited.
SD