Character dragging ground with it.

I have a character and a moving platform. The platform functions fine when the player is not moving. The platform defaults to moving left at a constant velocity. However when I move the character, it drags the platform along with it, so instead of the player moving, the platform and player are moving together with no player movement with respect to the platform. How would I get the player to not affect the platform velocity when moving? I have rigidbodies on both the player and the platform.

I really recomend you to use Transform.Translate instead of Rigidbody.addForce.
For the player:

void FixedUpdate()
	{
		transform.Translate (new Vector3(Input.GetAxis("Horizontal") * Time.fixedDeltaTime * speed,0,0));
	}

and for the ground:

void FixedUpdate()
	{

		transform.Translate (Vector3.left * speed * Time.fixedDeltaTime);

	}