Try doing a hard reset. In the settings menu. This happends to my phone to:/ it might just be the app itself or somthing. When you reset be sure to do the one where it keeps all data and files saved. :)) hhah I made this mistake before and it deleted my contacts and apps. :( if it persists take it to an apple store near you. I have one in town so it was an easy fix :DD haha. But if you don't have one near you, try sending it in during its warrenty before its to late. So they can replace/fix it. Also look up the troubleshooting for that. It could be a common thing?