I was told to do a couple of things.
First: Always make sure your tap water at the kitchen sink is hot before starting your dishwasher.
Second: Always run it on the high temp. scrub.
Third: Run your dishwasher w/out any dishes in it. Wait for the soap door to pop open (you can hear it after about a minute or so), then add 1 cup of vinegar to the water at the bottom and continue the cycle. That should help take a lot of the white film off the inside of your dishwasher. Wait about a week then do it again.
Fourth: Use a rinse agent, but mix it half and half with vinegar, and make sure the rinse agent is always full.
Fifth: Put only about a tablespoon of detergent in and put it in the pre-wash side, use about a tablespoon of Lemon Shine and put that where the detergent goes.
This won't completely fix your problem, but it will make a big difference.
Adam, December 2009