It happened multiple times last week while my wife's iphone 4 during Thanksgiving weekend. Got fed up and went to the ATT store. Got the microSIM replaced. So for the past 3 days, everything was good and dandy. However, my wife's iphone 4 again starts reading "no SIM" Her iphone 4 is in absolute mint condition. Never dropped. Never hacked. lastest iOS 4.2.1 software. I've seen multiple people have this problem. Do you think it's hardware related? I've got genius appt tomorrow afternoon after work.