This can happen during a loading or unloading operation and a jammed cassette can cause it, however if none of the above applies try lightly pressing on the cassette loading door, or alternatively have a try at this non technical procedure which sometimes get things working again in more than just JVC branded equipment, the procedure being to jolt the bottom of the camcorder in the palm of your hand, the reason for doing this being that electro-mechanical camcorders use position sensors in various places and sometimes although the mechanism looks to be fully home, electrically it isn't! and the jolt can on some occasions correct this problem.