Grind strawberries and cranberries in a food processor or grinder; place in a large kettle. Add sugar. Bring to a full rolling boil; boil for 1 minute. Stir in pectin; reutrn to a full rolling boil. Boil for 1 minute, stirring constantly. Remove from the heat. Cool for 5 minutes, skim of foam. Immediately pour into hot jars, leaving 1/4 inch headspace. Adjust caps. Process for 15 minutes in a boiling water bath.