In large bowl combine potatoes, corn, onion, garlic, oil and salt and pepper. Spread mixture evenly on a large cookie sheet.
Roast for 30-40 minutes or until potatoes are cooked and slightly crispy. Transfer to a large bowl and add chicken, toss lightly to combine. Set aside.
In a small bowl, combine mayonnaise, sour cream, parmesan cheese, horseradish, lemon juice and dill. Pour dressing over potato and chicken mixture. Toss well. Top with bacon.