Collider is deleting itself when I press play

So I am working on a little "start-up" project where I am making my own game. I'm still relatively a beginner, and thought I'd try to make a little something :). It is basically a player jet flying through a little gorge trying to kill as many enemies as possible while trying to stay alive. But I have a problem with the enemy game object. For ease, I duped the Player "Plane" object and renamed it to "Enemy", and took out the script for the player game object, and added a new script that deals with the enemy movement and shooting. The player has a box collider, which I have coded correctly to interact with the enemy collider. But the enemy Box collider deletes itself when I hit play. What's more, the actual component in the inspector disappears as well. I am so confused as to why this is happening, and have tried everything I can to fix it. I even tried re-doing the whole enemy game object, and replacing it with a new object and code, but that didn't work. I have some player boundaries, but they only interact with the player, and to make sure that this is the case, I have made it so that only objects with the tag "Player" are affected. I have been trying to fix this for about a week and it is so annoying!!

Please help if u can, thanks in advance!

Here is the code(which is all fairly similar) I use for the enemy, the code for destroying the player, removing the shots, and for destroying the enemy

Enemy code:

 using UnityEngine;
 using System.Collections;
 
 public class EnemySortOut : MonoBehaviour
 {    
     
     public GameObject Shot;
     public Transform ShotSpawn;
     public float FireRate;
     public float ForwardPush;
 
     private float NextFire;
     private Rigidbody rb;
 
     void Start () 
     {    
         rb = GetComponent<Rigidbody> ();
     }
     
 
     void FixedUpdate () 
     {
         if (Time.time > NextFire) 
         {
             NextFire = Time.time + FireRate;
             Instantiate (Shot, ShotSpawn.position, ShotSpawn.rotation);
         }
 
         rb.velocity = (transform.forward * ForwardPush);
     }

 }

Destroying the player:

 using UnityEngine;
 using System.Collections;
 
 public class PlayerDestroy : MonoBehaviour {
 
     public AudioSource PlayerDestroySound;
     public GameObject PlayerExplosion;
 
 
 
     void Start ()
     {
         PlayerDestroySound = GetComponent<AudioSource> ();
 
     }
 
 
     void OnTriggerEnter (Collider other) 
     {
         if (other.gameObject.tag == "Player") 
         {
             Instantiate (PlayerExplosion, other.transform.position, other.transform.rotation);
             PlayerDestroySound.Play ();
 
             Destroy (other.gameObject);
 
 
         }
 
     }
 }
 

Removing the shots:

 using UnityEngine;
 using System.Collections;
 
 public class ShotRemover : MonoBehaviour
 {
     void OnTriggerExit(Collider other)
     {    
         if (other.gameObject.tag == "Shot")
         {
             Destroy (other.gameObject);
         }
 
         if (other.gameObject.tag == "Player") 
         {
             other.gameObject.SetActive (false);
             other.gameObject.SetActive (true);
         }
     
     }
 
 }
 

Destroying the enemy:

 using UnityEngine;
 using System.Collections;
 
 public class EnemyDestroyer : MonoBehaviour 
 {
 
     public AudioSource EnemyDestroySound;
     public GameObject EnemyExplosion;
 
 
 
     void Start ()
     {
         EnemyDestroySound = GetComponent<AudioSource> ();
     
     }
     
     void OnTriggerEnter (Collider other) 
     {
         if (other.gameObject.tag == "Enemy") 
         {
             Instantiate (EnemyExplosion, other.transform.position, other.transform.rotation);
             EnemyDestroySound.Play ();
 
             Destroy (other.gameObject);
 
 
         }
 
 
 
     }
 
 }