You may face some problem in your mobile. Don't feel tensed when you face such kind of problem. Your mobile may hanged in different times.
Your mobile may restart many times. Your display may bilking sometimes. In your mobile there some problem appears different times. In this situation you don't need to go service center.
You should try yourself to recover this problem. In this condition you can reset your mobile by doing restore factory setting. In this way you can flash your phone memory. Then your maximum problem will be solved. You will get the option from phone setting or security setting. Make sure that for china mobile your reset password is 1122 and nokia mobile reset password is 1234. In this way you can try to solve your problem, your mobile may restarts after reset the setting. Then your problem is ok. Otherwise you can give software flash your mobile by going any service center. Then you can also go for customer care center for major problem.