opengl color problem

Hey,

In my program I'm drawing a square on the x-z plane RED in colour.

But, it appears MULTI-COLORED...

The drawing code is ...
angle+=1.0f;
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity (); glTranslatef (0.0f, 0.0f, -5.0f);
glRotatef(angle,1.0f,0.0f,0.0f);
glBegin(GL_QUADS);
glColor3f(1.0f,0.0f,0.0f); glVertex3f(0.0f,0.0f,0.0f);
glColor3f(1.0f,0.0f,0.0f); glVertex3f(GROUND,0.0f,0.0f);
glColor3f(1.0f,0.0f,0.0f); glVertex3f(GROUND,0.0f,-GROUND);
glColor3f(1.0f,0.0f,0.0f); glVertex3f(0.0f,0.0f,-GROUND);
glEnd();

To see what's happening plz download (only executable)

define MULTI-COLORED... like red and blue, or blue red and yellow, or different shades of red?

Are there any lights enabled? Lights can alter your colors