My iphone 4 keeps freezing every time i unlock it?

Everytime i unlock it, it freezes.
i know i can turn it off and on again but then it happens again.
is there a way i can stop this from happening with out taking it to the apple store?

You can try making a back up on your computer with itunes and then reseting it.

Hold the power and home button at the same time until the iPhone shuts down and keep holding until you see the Apple logo.