May be you are facing this issue due to some unwanted applications running in your device. These kind of activities sometime makes your device to perform weird functions or sometime make your device still or hanged. If there is some minor issue than it could be resolved through Soft Reset, you can soft reset your device by pulling out your device battery without switching off for 10-20 sec, then put it back. May be this would help you!!!!
Cheers:-$
