my gui text write over an over in a row

I have a skin (MySkin). How to solve this problem?

My script is here.

  using UnityEngine;
     using System.Collections;
     
     public class CarpismaScript : MonoBehaviour {
     
         public static bool isGameOver = false;
         public GUISkin skin;
     
         void Start () {
         
         }
         
         // Update is called once per frame
         void Update () {    
         
         }
         
         void OnGUI()
         {
                     GUI.skin = skin; //use the skin in game over menu
                     //check if game is not over, if so, display the score and the time left
                     if (!isGameOver) {
                             GUI.Label (new Rect (10, 10, Screen.width / 5, Screen.height / 6), "TIME LEFT: " );
                             GUI.Label (new Rect (Screen.width - (Screen.width / 6), 10, Screen.width / 6, Screen.height / 6), "SCORE: " );
                     }
                     //if game over, display game over menu with score
                     else {
                             Time.timeScale = 0; //set the timescale to zero so as to stop the game world
                 
                             //display the final score
                             GUI.Box (new Rect (Screen.width / 4, Screen.height / 4, Screen.width / 2, Screen.height / 2), "GAME OVER\nYOUR SCORE: ");
                 
                             //restart the game on click
                             if (GUI.Button (new Rect (Screen.width / 4 + 10, Screen.height / 4 + Screen.height / 10 + 10, Screen.width / 2 - 20, Screen.height / 10), "RESTART")) {
                                     Application.LoadLevel (Application.loadedLevel);
                             }
                 
                             //load the main menu, which as of now has not been created
                             if (GUI.Button (new Rect (Screen.width / 4 + 10, Screen.height / 4 + 2 * Screen.height / 10 + 10, Screen.width / 2 - 20, Screen.height / 10), "MAIN MENU")) {
                                     Application.LoadLevel (1);
                             }
                 
                             //exit the game
                             if (GUI.Button (new Rect (Screen.width / 4 + 10, Screen.height / 4 + 3 * Screen.height / 10 + 10, Screen.width / 2 - 20, Screen.height / 10), "EXIT GAME")) {
                                     Application.Quit ();
                             }
                     }
             }
     
         void OnCollisionEnter(Collision theCollision){
     
             if (theCollision.gameObject.name == "Base") {
     
                 isGameOver = true;
     
             }
         }
     }