Samsung u540 front buttons

Does anyone know how to turn off the front buttons? Everytime I answer the phone, and then hang up and try to put it back in my pocket, the front buttons are active and cause it to beep and try to do things just because my fingers or wallet touched them. Makes me crazy!

Press and hold the lock button with the phone closed (left side of the phone below the volume switch). A small lock symbol will appear, locking the media buttons.