I've had my GN2 for a little ove a week. I have have been experiencing the screen going dark and not responding or while using an app or on a call, the screen will go dark and/or freeze. I've had that happen 3-4 times on a call, and I can't end it. Even the power button doesn't work. If I leave a voice message and the screen goes dark or freezes, whereby I can't end the call, I can still hear the voice prompts so I know the call is still active. I really like the phone, but this is becoming frustrating. Is my phone defective? Anyone else having the same screen issue?