I don't think it's salt. This seems more like it's lime and the salt you put in your dishwasher doesn't dissolve it anymore or something.

Over here we have a very high concentration of lime into the tap water. That's why you have to put salt into your dishwasher. If you don't, you end of with dishes that look like you're showing on that photo.

I've bought a water softener to get it all out of the water before it gets used. Works VERY good, I'm real happy with it! I don't even need to put salt in the dishwasher anymore, it's completely superfluous.

edit: I've just read you don't have a salt dispenser in your dishwasher. Strange. I still believe it's the hardness of the water though. And this can change all of a sudden (if the water company changed their 'formula') and it can also be quite different in different areas.