I used to be able to use the Personal Hotspot feature to connect to the internet with my macbook pro just by using the airport card. Now when I try to do this, I get a message on my iPhone stating "Wi-Fi is Off. Personal Hotspot will only be available over Bluetooth and USB. Do you want to enable it over Wi-Fi." It then gives me the option to click on "Turn on Wi-Fi" or "Bluetooth and USB Only." If there is Wi-Fi available, I have no need to use the Personal Hotspot. I recently updated the iPhone firmware, so I'm not sure if this has anything to do with the problem.