If the product number of your camera is within the range below, refer to the following URL.
0010001 - 3000000
9000001 - 9330000
http://helpguide.sony.net/dsc/1740/v1/en/index.html
MENU 3 [Drop Sensor] desired mode
[Drop Sensor] function may activate even if you do not drop the camera, depending on how the camera is used.