Mix cereal, coconut and nuts. Place in a 13x9 inch pan. Cut margarine in squares and place on top. Bake at 300 degrees for 20 minutes, stirring every 7 minutes. Remove and stir in brown sugar. Cool. Leave half of mixture in 13x9 inch pan. Cut ice cream in squares and place over Rice Krispie mixture. Put rest on top and freeze. Cut in squares and serve. Randy Rigg