Smooth Mouse Script Problems

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
  
 [AddComponentMenu("Camera-Control/Smooth Mouse Look")]
 public class SmoothMouseLook : MonoBehaviour {
  
     public enum RotationAxes { MouseXAndY = 0, MouseX = 1, MouseY = 2 }
     public RotationAxes axes = RotationAxes.MouseXAndY;
     public float sensitivityX = 15F;
     public float sensitivityY = 15F;
  
     public float minimumX = -360F;
     public float maximumX = 360F;
  
     public float minimumY = -60F;
     public float maximumY = 60F;
  
     float rotationX = 0F;
     float rotationY = 0F;
  
     private List<float> rotArrayX = new List<float>();
     float rotAverageX = 0F;    
  
     private List<float> rotArrayY = new List<float>();
     float rotAverageY = 0F;
  
     public float frameCounter = 20;
  
     Quaternion originalRotation;
  
     void Update ()
     {
         if (axes == RotationAxes.MouseXAndY)
         {            
             rotAverageY = 0f;
             rotAverageX = 0f;
  
             rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
             rotationX += Input.GetAxis("Mouse X") * sensitivityX;
  
             rotArrayY.Add(rotationY);
             rotArrayX.Add(rotationX);
  
             if (rotArrayY.Count >= frameCounter) {
                 rotArrayY.RemoveAt(0);
             }
             if (rotArrayX.Count >= frameCounter) {
                 rotArrayX.RemoveAt(0);
             }
  
             for(int j = 0; j < rotArrayY.Count; j++) {
                 rotAverageY += rotArrayY[j];
             }
             for(int i = 0; i < rotArrayX.Count; i++) {
                 rotAverageX += rotArrayX[i];
             }
  
             rotAverageY /= rotArrayY.Count;
             rotAverageX /= rotArrayX.Count;
  
             rotAverageY = ClampAngle (rotAverageY, minimumY, maximumY);
             rotAverageX = ClampAngle (rotAverageX, minimumX, maximumX);
  
             Quaternion yQuaternion = Quaternion.AngleAxis (rotAverageY, Vector3.left);
             Quaternion xQuaternion = Quaternion.AngleAxis (rotAverageX, Vector3.up);
  
             transform.localRotation = originalRotation * xQuaternion * yQuaternion;
         }
         else if (axes == RotationAxes.MouseX)
         {            
             rotAverageX = 0f;
  
             rotationX += Input.GetAxis("Mouse X") * sensitivityX;
  
             rotArrayX.Add(rotationX);
  
             if (rotArrayX.Count >= frameCounter) {
                 rotArrayX.RemoveAt(0);
             }
             for(int i = 0; i < rotArrayX.Count; i++) {
                 rotAverageX += rotArrayX[i];
             }
             rotAverageX /= rotArrayX.Count;
  
             rotAverageX = ClampAngle (rotAverageX, minimumX, maximumX);
  
             Quaternion xQuaternion = Quaternion.AngleAxis (rotAverageX, Vector3.up);
             transform.localRotation = originalRotation * xQuaternion;            
         }
         else
         {            
             rotAverageY = 0f;
  
             rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
  
             rotArrayY.Add(rotationY);
  
             if (rotArrayY.Count >= frameCounter) {
                 rotArrayY.RemoveAt(0);
             }
             for(int j = 0; j < rotArrayY.Count; j++) {
                 rotAverageY += rotArrayY[j];
             }
             rotAverageY /= rotArrayY.Count;
  
             rotAverageY = ClampAngle (rotAverageY, minimumY, maximumY);
  
             Quaternion yQuaternion = Quaternion.AngleAxis (rotAverageY, Vector3.left);
             transform.localRotation = originalRotation * yQuaternion;
         }
     }
  
     void Start ()
     {            
         if (rigidbody)
             rigidbody.freezeRotation = true;
         originalRotation = transform.localRotation;
     }
  
     public static float ClampAngle (float angle, float min, float max)
     {
         angle = angle % 360;
         if ((angle >= -360F) && (angle <= 360F)) {
             if (angle < -360F) {
                 angle += 360F;
             }
             if (angle > 360F) {
                 angle -= 360F;
             }            
         }
         return Mathf.Clamp (angle, min, max);
     }
 }

So this is the smooth mouse look script from the wiki, here: http://wiki.unity3d.com/index.php?title=SmoothMouseLook

This is my error, while it works fine, whenever I replace the First Person Controller mouselook with this, I have an issue where when I look straight down or straight up the camera gets stuck for a moment, but if I try to pull back up I can after about a second or two. However, if I continue to try to move the mouse down while it is straight down it will become permanently stuck there.