Sprinkle chicken with salt and pepper and place in crockpot. Combine ginger, garlic, broth and syrup from pineapple. Cut pineapple slices into fourths. Arrange pineapple and water chestnuts (sliced) over chicken. Pour ginger sauce over all. Cover and cook on low 3-4 hours, or until tender. Add green onions. Dissolve cornstarch in soy sauce and vinegar. Stir into pot. Cover and cook on high 10-15 minutes or until slightly thickened. Serve with crisp Chinese noodles.