Remove the sim card that is associated to phone like it was line phone Press the power on and hold the down button immediately for 10 to 20 seconds. While holding the phone will reboot and reboot and reboot again and will reboot in safe mode. After rebooting in safe mode wait for a while ans press the notification and turn the phone "safe mode off" The sim card registration is the suspected problem why this happens every time the sim card was change or inserted something need to be registered...and also the system of the phone is poor that cannot handle some errors.