I installed Whatsapp yesterday. Love the app, but I've noticed that my screen no longer gives the slight vibration known as 'haptic feedback' when I touch an icon (the bottom section of the screen, the 4 'home' keys, still does.) I have feedback turned on and have tried unchecking the box, then checking it again to try to 'turn it back on,' to no avail. I've installed no other software and wonder if this problem is tied somehow to the Whatsapp app. Thanks!