My mother bought a new iPhone 4 last week and it has worked flawlessly except for some reception problems, which I will address in a separate thread. While checking her email yesterday, the screen on her iPhone went completely black all of a sudden. She tried pressing/holding the home and sleep buttons but the phone would not respond. I'm wondering if my mother's phone is defective and whether we should exchange it before these problems become more frequent She brought it back to the AT&T store where they connected to a computer and "fixed" it. I assume they did a restore. She asked them what was wrong with the phone and they said they had no idea. Has anyone else experienced this problem before? What could have caused this? Her phone was brand new with zero apps installed. The only modification she made out of the box was updating to iOS 4.0.2 My sister also experienced a similar black screen but she was able to restart the phone by holding down the home and sleep buttons. Her phone came in the same AT&T shipment as my mother's last week. My iPhone was purchased from an Apple Store. No problems so far.