Philips have let it be known that some Wi-Fi card and iPronto combinations are prone to lockups in some situations. Personally I expect it is more to do with how the card talks to the access point. It may be worth running the wi-fi network without WEP switched on to see if that helps. (You can always use MAC filtering in the Access Point to maintain some kind of security). I am also suspicious that the SSID can be a factor. Try setting the SSID on the Access Point and the iPronto to be very simple. i.e. don't use spaces or any other punctuation, stick with letters and numbers. Changing this helped my setup to be more stable.