How to make this shader for a particle system work with HDR?

I'm using this shader for a particle system which when coupled with HDR becomes artifacted/inverted (alpha-blending issues I think). Judging by similar issues others have had, I'm hoping someone here knows how to rectify this shader script.

 Shader "LemonSpawn/LazyFog" {
     Properties {
         _Color ("Color", Color) = (1,1,1,1)
         _MainTex ("Albedo (RGB)", 2D) = "white" {}
         _Scale ("Scale", Range(0,5)) = 1
         _Intensity ("Intensity", Range(0,1)) = 0.5
         _Alpha ("Alpha", Range(0,2.5)) = 0.75
         _AlphaSub ("AlphaSub", Range(0,1)) = 0.0
         _Pow ("Pow", Range(0,4)) = 1.0
     }
 SubShader {
         Tags {"Queue"="Transparent+101" "IgnoreProjector"="True" "RenderType"="Transparent"}
         LOD 400
 
 
         Lighting On
         Cull Off
         ZWrite Off
         Blend SrcAlpha OneMinusSrcAlpha
        Pass
          {
 
          
              CGPROGRAM
             
              #pragma target 3.0
              #pragma fragmentoption ARB_precision_hint_fastest
              
              #pragma vertex vert
              #pragma fragment frag
              #pragma multi_compile_fwdbase
              
              #include "AutoLight.cginc"
              #include "UnityCG.cginc"
                          
 
              sampler2D _MainTex;
              float4 _Color;        
              float _Scale;
              float _Intensity;
              float _Alpha;
              float _AlphaSub;
              float _Pow;
             
              struct v2f
              {
                  float4 pos : POSITION;
                  float4 texcoord : TEXCOORD0;
                  float3 normal : TEXCOORD1;
                  float4 color: TEXCOORD2;
                  float2 uv : TEXCOORD3;
                  float3 worldPosition: TEXCOORD4;
  
              };
               
              v2f vert (appdata_full v)
              {
                  v2f o;
                  o.pos = mul( UNITY_MATRIX_MVP, v.vertex);
                  o.uv = v.texcoord;
                  o.normal = normalize(v.normal).xyz;
                  o.texcoord = v.texcoord;
                   o.worldPosition = mul (_Object2World, v.vertex).xyz;
                  o.color =v.color;
         //         TRANSFER_VERTEX_TO_FRAGMENT(o);
                  
                  return o;
              }
 
         fixed4 frag(v2f IN) : COLOR {
             float3 worldSpacePosition = IN.worldPosition;
             float3 N;
             float3 distScale = 0.5;        
             float3 viewDirection = normalize(_WorldSpaceCameraPos - worldSpacePosition);
             float dist = clamp(pow(length(0.1*distScale*(_WorldSpaceCameraPos - worldSpacePosition)),1.0),0,1);
             float scale = 5;
             float shadowscale = 1;
             float4 c = tex2D(_MainTex, IN.uv*_Scale);
             float xx = c.r*_Intensity;
             xx = pow(xx,_Pow);
             c.a = c.r;            
             c.rgb = float3(xx*_Color.r,xx*_Color.g,xx*_Color.b);    
             c.a *= IN.color.a-2.5*length(IN.uv-float2(0.5, 0.5));
             c.a*=_Alpha;
             c.a-=_AlphaSub;
             return c;
             
              }
              ENDCG
          }
     }
  }