When I allow my Eris to connect to my home wireless network, my wife's netbook suddenly drops connectivity and cannot get reconnected reliably until I turn the Eris wireless off.
Or is your wife's netbook set for 802.11n ONLY? If you don't have a dual g/n router, it would throttle back to g only when the Eris pings it, cutting off the netbook. Could be a lot of things, actually.