Screen freezes after running the game [ Shaders problem ]

i'm using the shader below, whene i run the game. it renders one frame and then stops rendering and updating screen, the other scripts are working fine without any problem.

 Shader "The Developer/SS All-in-One Outline"
 {
     Properties
     {
         _OutlineColor("Outline Color", Color) = (1,1,1,1)
         _OutlineThreshold("Outline Threshold", Float) = 3
         _OutlineWidth("Outline Width", Float) = 2
         _DepthMultiplier("Depth Multiplier", Float) = 2
         _EdgeStrengthen ("Edge Strengthen", Float) = 2
         _MainTex ("Texture", 2D) = "white" {}
     }
     SubShader
     {
         // No culling or depth
         // Cull Off ZWrite Off ZTest Always
 
         Pass
         {
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #include "UnityCG.cginc"
 
             struct appdata
             {
                 float4 vertex : POSITION;
                 float3 normal : NORMAL;
             };    
 
             struct v2f
             {
                 float4 position : POSITION;
                 float4 screenPos : TEXCOORD0;
             };
 
             fixed4 _OutlineColor;
             half _OutlineThreshold;
             half _OutlineWidth;
             half _DepthMultiplier;
             half _EdgeStrengthen;
             sampler2D _CameraDepthTexture;
             sampler2D _MainTex;
 
             v2f vert(appdata input)
             {
                 v2f output;
 
                 output.position = UnityObjectToClipPos(input.vertex);
                 output.screenPos = output.position;
 
                 return output;
             }
 
             #define PSL01UVC(uv1, uv2) \
                         pow((Linear01Depth(tex2D(_CameraDepthTexture, uv1)) - Linear01Depth(tex2D(_CameraDepthTexture, uv2))), 2) + \
                         pow((SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, uv1) - SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, uv2)) * _DepthMultiplier, 2) + \
                         pow((tex2D(_MainTex, uv1) - tex2D(_MainTex, uv2)) * _EdgeStrengthen, 2)
 
             float4 outline;
             half4 pixel;
             half2 uv;
             half onePixelW, onePixelH;
             fixed i;
             void OutlinePixel(){
                 outline = 0;
                 for(i = 1 ; i <= _OutlineWidth ; i++){
                     outline += 
                             PSL01UVC(half2(uv.x - i * onePixelW, uv.y), 
                                      half2(uv.x + i * onePixelW, uv.y)) + 
 
                             PSL01UVC(half2(uv.x, uv.y + i * onePixelH), 
                                      half2(uv.x, uv.y - i * onePixelH)) + 
 
                             PSL01UVC(half2(uv.x - i * onePixelW, uv.y - i * onePixelH), 
                                      half2(uv.x + i * onePixelW, uv.y + i * onePixelH)) + 
 
                             PSL01UVC(half2(uv.x - i * onePixelW, uv.y + i * onePixelH), 
                                      half2(uv.x + i * onePixelW, uv.y - i * onePixelH));
                 }
             }
 
             half4 frag(v2f input) : SV_Target
             {    
                 uv = input.screenPos.xy / input.screenPos.w;
                 uv.x = (uv.x + 1) * .5;
                 uv.y = (uv.y + 1) * .5;
 
                 pixel = tex2D(_MainTex, uv);
 
                 onePixelW = 1.0 / _ScreenParams.x;
                 onePixelH = 1.0 / _ScreenParams.y;
 
                 OutlinePixel();
 
                 return lerp(pixel, _OutlineColor, (outline.r + outline.g + outline.b) >= _OutlineThreshold ? 1 : 0);
             }    
             ENDCG
         }
     }
 }