Character starts walking automatically, without any input - unity3d

Question

I have a problem with Unity 4.0.0. When I play the AngryBots project or even when I make my own char with a simple walking script, it automatically walks without pressing any button.
I tried to uninstall Unity, I tried it with an older version of Unity, I even deleted it from the registry, but I still get the same behaviour. Why does that happen? Is it a bug, or am I doing something wrong?
var speed = 6.0;
var jumpSpeed = 8.0;
var gravity = 20.0;
private var moveDirection = Vector3.zero;
private var grounded : boolean = false;
function FixedUpdate() {
if (grounded) {
// We are grounded, so recalculate movedirection directly from axes
moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, 0);
moveDirection = transform.TransformDirection(moveDirection);
moveDirection *= speed;
if (Input.GetButton ("Jump")) {
moveDirection.y = jumpSpeed;
}
} // Apply gravity
moveDirection.y -= gravity * Time.deltaTime;
// Move the controller
var controller : CharacterController = GetComponent(CharacterController);
var flags = controller.Move(moveDirection * Time.deltaTime);
grounded = (flags & CollisionFlags.CollidedBelow) != 0;
}
#script RequireComponent(CharacterController)
I am using this script for all my walking chars and it works, but now its walking automatically.

Answer 1

The issue is something is providing movement axis input.
Generally it will be another device such as joystick etc. First step will be to unplug any other input devices you might have to test (Isolate the problem - then fix as required)
Another thing that may be causing it: I had the same issue but no other input devices plugged in. I found that a driver called VJoy virtual joystick (Installed as part of FreetrackNoIR) was setting movement axis values to 1 and -1 for each axis, thus resulting in the same problem.
Disabling this driver (Control panel, device manager, Human Interface devices) fixed it for me!
Good luck.

Answer 2

You have to use an "Animation" component, not an "Animator" one. (You can assign this by clicking on "Add Component", "Miscellaneous" and "Animation." This will contain the "Play Automatically" button you need.

Answer 3

I had this same thing happen to me. My characters would go UP and LEFT when I would move my mouse off of the Game window while in the editor and in my builds.
Go to "Edit, Project Settings, Input" and verify that your Horizontal and Vertical are set accordingly. Once I deleted the second set of inputs for Horizonal and Vertical in the InputManager, it stopped doing that.