just got an iphone 4, when i plug it into my mac, the mac jumps to iTunes and the speaker on the iphone stops working. it stays not working while i toggle the mute switch. i tried a lot of forums, tried plugging and unplugging the headphones, that didn't help (although sound works fine through the headphones). the only cure seems to be to plug it into the mains charger when it starts working again. anyone encounter this before? the only apps i installed are hipstermatic and a star chart app. no pandora or anything like it. this isn't an end of the world problem because i can fix it but i'd still like to know what the hell is going on. while it's silent, the volume control is on full volume. itunes on the phone doesn't make any sound, neither does the system eg changing the ringtone. thanks for any suggestions.