I'm having a strange issue with my 4s. I've had the phone for over a year and it's done this a couple of times. When I try to unlock the phone it doesn't work. I slide my finger across the screen and nothing happens. If I unlock the camera I can get into my phone. Now currently the phone does have a Lifeproof case on it. However this was happening before I installed the case on the phone (2 weeks ago). When I had a simple screen protector on it the same thing would happen. It's a weird little thing that just annoys me and might be a bigger issue or nothing at all.