I am having a problem with my iPhone 5. Sometimes, even when the silence switch is flipped on (sound on, red mark not visible), it does not play sounds. This includes keyboard clicks, lock sounds, text tone when receiving texts, etc. Toggle back and forth between silent on/off does nothing. Every time this happens, if I turn off my phone and turn it back on, the problem is fixed. But otherwise, the problem continues. Anyone have this problem?