We have a 2 year old dishwasher in a 20 year old home. I use a water softner, cascade liquid or solid, and solid Jet Dry. Typically after doing a load, a white powder will remain on the dishes. It is heaviest on the top rack, and is very heavy where dishes are in contact with the rack or each other. If I do a quick rinse cycle with some vinegar, it will clean the whole load. This problem is intermittent. I will do a week or so with a problem, then it will return for a week or two. The dishwasher itself is working fine and the water is very hot. Can anyone help me out here? Thanks.