Q8. Should I allow Windows XP to manage my wireless settings?
A8. Probably not. When you are not connected to a network, XP will cycle through your favorite network names attempting to connect to them. While this is happening, NetStumbler may not see all available networks. It is recommended that you stop the "Wireless Zero Configuration" service while NetStumbler is running. You can do this by switching on "Auto Reconfigure", from Control Panel, or by running the command "net stop wzcsvc".
http://www.stumbler.net/readme/readme_0_4_0.html