Script crashes Unity

The following script is attached to the player and it crashed Unity.

 #pragma strict
 
 var invulTime : float;
  
 function Update () {
     invulTime -= Time.deltaTime;
     RespawnInvulnerability();
 }
 
 function OnCollisionEnter(Col : Collision){
     invulTime = 1;    
 }    
 
 function RespawnInvulnerability(){
     if (invulTime > 0 && invulTime < 1){
         collider.enabled = false;
         print("invul ON");
     }
     if (invulTime <= 0){
         collider.enabled = true;
         print("invul OFF");
     }
 }

I'm not that great with coding, so there's probably a better script to do t$$anonymous$$s with. But what t$$anonymous$$s does is it constantly counts down the invulTime below zero, w$$anonymous$$ch means that the collider is enabled. When the player gets $$anonymous$$t it sets the invulTime to 1, w$$anonymous$$ch means that the collider is disabled in the window between 1 and 0 of invulTime. When the player gets $$anonymous$$t it detracts a life from the player and resets the player's position to the start position of the player. T$$anonymous$$s script then gives the player a second of invulnerability to get going again.

It happens when I'm playing the game in the Unity Game window, the 3 lives are depleted (consequently the player is destroyed) and the Game Over GUI (with a couple of boxes and buttons, Time.timeScale is 0 as well then) is overlayed and $$anonymous$$t the play button again to stop playing. The $$anonymous$$tting of the play button crashes Unity. Also, $$anonymous$$tting the Retry button (Application.LoadLevel(Application.loadedLevel)) in the Game Over GUI crashes Unity as well.

The following error is displayed: Unity.exe caused an Access Violation (0xc0000005) in module Unity.exe at 001b:012bf610.

Is there somet$$anonymous$$ng wrong with t$$anonymous$$s script? Perhaps you have an alternative way of doing what I want to do, w$$anonymous$$ch possibly won't crash Unity?

I also tried the following, t$$anonymous$$nking the constant detracting of Time.deltaTime might be causing it, w$$anonymous$$ch didn't fix the issue.

 #pragma strict
 
 var invulTime : float;
 
 function Update () {
 
     if (invulTime <= 1 && invulTime >= 0){
         invulTime -= 0.01;
     }
 
     RespawnInvulnerability();
 }
 
 function OnCollisionEnter(Col : Collision){
     invulTime = 1;    
 }    
 
 function RespawnInvulnerability(){
     if (invulTime > 0 && invulTime < 1){
         collider.enabled = false;
         print("invul ON");
     }
     if (invulTime <= 0){
         collider.enabled = true;
         print("invul OFF");
     }
 }

Thanks for your time!