Character goes crazy when pressing play

Hey, I m currently making a endless runner game but I bumped into a problem, I dont know how to fix. the problem is that the character goes crazy bounces,bumps into objects… anything is helpful… thanks.

script:

using UnityEngine;
using System.Collections;

public class PlayerMotor : MonoBehaviour 
{
	private CharacterController controller;
	private Vector3 moveVector;

	private float speed = 5.0f;
	private float verticalVelocity = 0.0f;
	private float gravity = 5.0f;
		
	private float animationDuration = 3.0f;

	private bool isDead = false;

	// Use this for initialization
	void Start () {
		controller = GetComponent<CharacterController> ();
	}

	// Update is called once per frame
	void Update () {


		if (isDead)
			return;
		
		if (Time.time < animationDuration) {
			controller.Move (Vector3.forward * speed * Time.deltaTime);
			return;
		}

		moveVector = Vector3.zero;

		if (controller.isGrounded) {
			verticalVelocity = -0.5f;
		} else {
			verticalVelocity -= gravity * Time.deltaTime;
		}

		// X - Left and Right
		moveVector.x = Input.GetAxisRaw ("Horizontal") * speed;

		// Y - Up and Down
		moveVector.y = verticalVelocity;

		// Z - Forward and Backward
		moveVector.z = speed;

		controller.Move (moveVector * Time.deltaTime);
	}

		public void SetSpeed(float modifier)
		{
			speed = 5.0f + modifier;
		}
	// It is beign called every time our capsule hits something
	private void OnControllerColliderHit (ControllerColliderHit hit)
	{
		if (hit.point.z > transform.position.z + controller.radius)
			Death ();
	}

	private void Death ()
	{
		isDead = true;
			GetComponent<Score> ().OnDeath ();
	}
}

I would check for collider clipping or problems with your characters bone structure/rig/joints.