i brought my 9900 for half a year now,i've done some battery pull without turning the device off cuz the phone just stopped and stuck a app or homescreen.my battery can stand over 5 hours,i've install every OS but doesn't help any and recently my phone always hang,i've clean my memory but just the same.i've even took my phone to the carrier for a check but they said my phone dun have any problem.so what should i do?