I spent several very frustrating hours today wrestling with an Apple software update for my 12 inch PowerBook G4. The Airport 3.1 update makes my Airport Extreme card somehow incompatible with my SMC 802.11b access point. The PowerBook can see the access point, but I receive a message that says “An error occurred while joining the selected Airport network.” I had to reinstall OS X in order to get things working again, as there seems to be no way to roll back the update.