I've been having this weird problem at home with my wireless network. I have a Windows Vista Ultimate laptop (Lenovo Thinkpad T61p) and a Netgear RangeMax WNR854T wireless router. In 'Network & Sharing Centre' on Vista, it shows that I have two network connections to the same wireless network. Both show I'm connected to local and internet. One connection is continuously identified as an 'Unidentified Network', the other is as it should be with my settings in place.
View Status shows the same status, and Disconnect disconnects both connections. When I reconnect, it creates the dual network connections again. This would be just a curiosity but it seems to be really slowing my connection, so I'm going to have to find out what's going on.
So, success at last with a solution but not a reason that I can pinpoint.
Having tried turning on and off IPv4 and IPv6 connectivity, NETBIOS, file and print sharing and just about every other combination I could come up with, I tried a static IP and low and behold I now only have one wireless network connection and the speed is back to normal.
Very strange, but at least it's resolved.