This is driving me nuts!
I have the Nintendo USB dongle attached to my PC, which my DS connects through... no problem.
Got my Wii today (Euro launch ), and tried to register it.
No problems with the registration itself, but when I test the connection it always fails (error 51340 I think: WEP key has changed blah blah).
However if I plug the dongle in to another PC and register the Wii it works fine. So I can only assume it something with my PC.
I run ZoneAlarm, but have tried disabling that before running the test same problem.
Anyone got any ideas?