Camera Script Rolling on the Z

Hi All, I wrote this amazing script (stole it) and have modified sections (ripped it appart) to make it work as I want it to (it isn't working)

All jokes aside, I am attempting to rotate the camera around the screen with it's focus on a target. The rotation happens on a mouse drag. The rotatin is full 360. The problem is that the camera swivles on the Z axes as well as the x and y.

Please can someone help me out here. I basically take the code below, and attatch it to the Main Camera.

using UnityEngine; using System.Collections;

public class CameraControl : MonoBehaviour {

 public Transform target;
 public float xSpeed = 125.0f;
 public float ySpeed = 50f;

 public float  resetTime = 1.0f; //How long to take to reset

 private Vector3 startDirection = Vector3.zero; //How far away to orbit

 private float x = 0.0f; 
 private float y = 0.0f;
 private float z = 0.0f; 

 private Quaternion startRotation;
 private Quaternion rotation;

 private bool resetting = false;
 private float resetTimer = 0.0f;

 void LateUpdate()
 {
     if (Input.GetMouseButtonDown(0))
     {    startDirection = (transform.position - target.position);
         startRotation = transform.rotation;
         x = 0.0f;
         y = 0.0f;
         z = 0.0f;
     } 

     if (Input.GetMouseButton(0))
     {
         x += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
         y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;
         z = 0.0f;
         Reorient();
     } 
 }

 void Reorient()
 {
     rotation = Quaternion.Euler(y, x, z);
     transform.rotation = rotation * startRotation;
     transform.position = rotation * startDirection + target.position;
 }

}