We had the same problem about a month ago. The service man told us to only use powder detergent and make sure you don't fill both dispensers full. Try using only 2-3 or so tablespoons each side to start. Also use the liquid Jet-Dry in the built-in dispenser (if you have one). And run the water in the faucet til its very hot before you start the dishwasher so the first cycle works using hot water.
The thing that really did the trick is a product called Glass Magic. Most grocery stores carry it. You just dump 1/4 cup in the bottom of your dishwasher and run the cycle. If the build-up is bad you may have to do it 2-3 times initially and then 1-2 times a month or as needed.