Samsung MM-A900 / SPH-A900 / Ace

Its because you uploaded an image to the phone. Don't use the internet to upload an image, it can't handle it. You have to use the USB cable and then ONLY store the pictures in the folder that the phone stores pictures it takes with its own camera. Otherwise it will freeze like that and you can't even push button when in an automated system cause the frozen phone won't send the tones. Just a flaw they over looked. I went through 3 phones sending each one back before I figured it out. Also, don't update the phone to the newest firmware! Thats part of the problem too!