I ran into the same thing a year or so ago. I had used a cheaper brand of dishwasher detergent and found little gummy spots on my dishes. I have no idea if it was the change of detergents. After many many cycles with clorox and or vinegar it was finally cleaned out. These were empty cycles with just clorox or vinegar or both. I also have started using a cleaner (found at Walmart) once a month and returned to using Cascade and have not had this problem since. Did i mention it took Many Many Many cycles using Clorox and white vinegar. Good luck.