Combine cereal, cashews and coconut in a large heat-proof bowl; set aside. Melt butter in a large saucepan over medium heat; add corn syrup and brown sugar. Stir well and bring to a boil; boil for 5 minutes. Remove from heat; stir in vanilla and baking soda. Pour over cereal mixture; stir well to coat. Pour mixture out onto a greased 15"x10" jelly-roll pan. Bake at 250 degrees for one hour, stirring every 15 minutes. Store in an airtight container.