Wireless Networks Tab kills Explorer

[OldCodger]

I am endeavoring to up the security level across my wifi n/w - 5 machines, 3 desktops (multi-boot Win98SE/XP + Linux), a laptop and a netbook (each multi-boot Vista/XP + Linux) from WEP to WPA2 (and eventually from manual to automatic configurations). To this end my XPs have been SP3ed and the nic changed on two of the desktops. For consistency, I am setting the desktops to use WZC - the other two are by default.

All is well except that one machine, clicking the Wireless Networks Tab causes Explorer to crash (and very difficult to recover even via task manager).

Although the problem seems to have occured since SP3, the mystery deepens in that another machine has exactly the same mobo and nic and SP3 yet there is no problem.

"sc query wzcsvc" shows that WZC is running normally and my connection is working fine except for this wretched promlem?!

Please note that in Win98 all works fine but would also remark that the graphics are much smoother there than in XP. Is there a clue there? Although the nic is in slot 3 (as was the original nic) they do share an irq - as on other machines - but there are no reported conflicts.