Turn Your iPhone OFF and Back on. To do this Hold the sleep button on the top down till you get a slider then slide it OFF. Then just click that same button again to restart.You are running a Mini Computer. This Mini Computer DOES NOT close its applications when it is done so after awhile you have A LOT of stuff stacked up. Just like any other computer, sometimes it just needs a reboot. So if you have apps closing on their own or the slider to unlock is starting to get a little funny.....just turn it off and back on. Should help a lot.