Flipping parent object in 2d with negative x scale causes rotation issues for children gameobjects

When I flip my my parent game object from positive x to -x image size to mirror and make it appear as if the image went from moving left to right, the children game objects no longer rotate properly when using a rotation script. It appears that it isn't just rotating improperly but rotating in a weird way altogether. I'm using Unity 4.5.1f3, I know there was a problem with 2d collider rotation but this seems to be outside of that because the entire game object is rotating abnormally.

Does anyone know how to overcome this problem?

Script for arm rotation, arms are attached to parent game object. When the parent flips size from positive to negative, the image mirrors and all children flip as well, but when rotating, problems occur:

 void Update ()
     {
         target = this.transform;
         mouse_pos = Input.mousePosition;
         mouse_pos.z = 0f; //The distance between the camera and object
         object_pos = gameManager.mainCamera.WorldToScreenPoint(target.position);
         mouse_pos.x = mouse_pos.x *-1.0f - object_pos.x;
         mouse_pos.y = mouse_pos.y - object_pos.y;
         angle = Mathf.Atan2(mouse_pos.y, mouse_pos.x) * Mathf.Rad2Deg;
         transform.rotation = Quaternion.AngleAxis( angle+105.0f, Vector3.forward);

      }