Do not thaw corn and omit butter. In a 3 1/2- or 4-quart slow cooker combine frozen corn, sweet peppers, onion, and black pepper. In a medium bowl whisk together celery soup, cream cheese, and milk. Pour over mixture in cooker. Cover and cook on low-heat setting for 8 to 10 hours or on high-heat setting for 4 to 5 hours. Stir before serving.