How do I clean the interior of my dishwasher to remove white residue?

Whirlpool recommends monthly use of affresh® Dishwasher Cleaner to remove white residue buildup; place one tablet in the detergent dispenser (without detergent) and run a Normal wash cycle. Alternatively, you can place 2 cups (500 mL) of white vinegar in a dishwasher-safe measuring cup on the bottom rack and run a complete washing cycle using an air-dry or energy-saving dry option without detergent. However, vinegar is an acid and using it too often could damage your dishwasher. (Page 13)