I have experienced a problem with my iphone over the past few months, in that every few days the phone will become non responsive. It will work fine and then the next time I attempt to use it the screen will not appear. When I switch to vibrate nothing will happen. When this happens I can not turn the phone off. To remedy this problem, I must plug my Iphone to a charger, get the screen to come on, then turn it off. After turning the phone back on everything is okay, until the problem occurs a few days later. Has anyone experienced this problem, or know of a solution?