EDIT: Also, failed to mention, big fail here, replace your SIM then do the following... Try a DFU restore of your device and SET IT UP AS NEW. First make sure your contacts are sync'd with another program on your computer, i.e. addresbook.app, Win Address Book, Windows Contacts, or Outlook. That way you can resync them to your iphone after the process. Connect iphone to your computer while iTunes is open. HOLD Home & Sleep/Wake button for exactly 8 sceonds. (I used a stopwatch or timer on the computer) The timing here has to be EXACT otherwise it will NOT work. RELEASE Sleep/Wake and continue to HOLD Home for another 5-10 seconds. iTunes will pop and tell you iphone is in recovery mode and must be restored. iPhone is really in DFU mode, not standard recovery mode. You will know you've got it because your iPhone's display will stay blank and when you start the restore it will flash white. Click restore. Let iPhone restore. Set iPhone up as new and RESYNC your content. DO NOT RESTORE FROM BACKUP AFTER THIS PROCESS UNDER ANY CIRCUMSTANCES. I can't promise 100% it will work for every iphone with problems, but it has worked for myself and many others who I know. I sincerely hope this helps someone.