Postprocess defects

As I use my postprocessing by rendering a single quad

1. When I dont apply any 2d effects in pixel shader , there are very slight
defects in borders of the screen , I am not giving any screenshot because
it is very hard to see in screenshots.

2. When I apply a simple blur effect , there is a clear problem on the right side of the screen :

Original Defect appears with blur



You can see simple blur code as below :



float4 BlurPS(in V2P IN) : COLOR0
{
float4 Color = tex2D(ColorSampler, IN.TexCoord);
Color += tex2D(ColorSampler, IN.TexCoord + float2(0.010f, 0.0f));
Color += tex2D(ColorSampler, IN.TexCoord + float2(0.020f, 0.0f));
return Color/3;
}



And the color sampler :



sampler ColorSampler = sampler_state
{

Texture = <diffuseTexture>;

MinFilter = LINEAR;

MagFilter = LINEAR;

MipFilter = LINEAR;

};