hi, i got my iphone 4 about 3 weeks ago, already had one replacement this is the second one. every other day at night or day (mostly at night) the phone just turns off. like the screen is black and no buttons work. i have to push and hold home and lock several times for like 10 seconds and after 2-3-4 tries it restarts and works again. this morning i had to restart it 5 times from 4am to 7am and since then i didn't had to restart it. battery is full and i already tried to reset it back to stock and its still there. sometimes its everyday, sometimes its several times a day and sometimes its just every other day or later. really weird. i read about it before sometimes but no one never found a solution.