Line 9x13" pan with foil so that foil extends over sides; butter foil. In large bowl, combine popcorn, nuts and cranberries; set aside. In medium saucepan, combine margarine and marshmallows. Cook over low heat until marshmallows are melted, stirring constantly. Pour over popcorn mix; mix well. Press mixture in foil lined pan. Sprinkle with chocolate chips; press lightly. Refrigerate 1 hour to cool. Remove from pan by lifting foil; remove foil from mixture. Cut into 36 bars.