I keep getting an error message that says "Unfortunately the process android.process.acore has stopped". It keeps popping up so that I can't do anything with the phone, including a total power off. I searched this error and read some suggestions to get rid of it, but I can't get my phone to do anything, because as soon as I hit "Ok" it comes back again immediately! Can't reboot, nothing! Any suggestions what I can do to fix this?