IPhone blank screen and can't hard reset
I've had my iphone for 2 weeks, and the screen has just started going blank, and I can't use it. I've tried had resetting it, and it reboots, but the screen still doesn't work. I'm using 3.1.2. It only starts working again when I restore it. It works for about a day, then it gets into this state. It' still on as when I switch the mute button it vibrates. Is this a hardware problem?
It's basically brand new, and is a replacement for my other brand new phone that didn't have any sound straight off the bat!
17 inch MBP, Mac OS X (10.4.6), 1GB 100GB 7200RPM