Shader error: Shader program of type 'vp' already exists at line ....

Hi All, Couldn't find the answer to this one anywhere. Am I missing something obvious or does GLSL not work for anyone else?

I tried to make the smallest shader but it gives me the following error:

Shader error in 'MinShader': 
Shader program of type 'vp' already exists at line 52

The shader Im using:

Shader "MinShader" {
    Properties {
        _Color ("Main Color", Color) = (1,1,1,1)
    }
    SubShader {
GLSLPROGRAM
        #ifdef VERTEX
        void main() {
        }
        #endif
        #ifdef FRAGMENT
        void main() {
        }
        #endif  
ENDGLSL        
    } 
    FallBack "Diffuse"
}