Dishwasher salt build up

I have an Indesit dishwasher (a pretty basic one) and the dishes mostly come out with a white cloudy film on them. I have not put any salt in it for ages, but if I taste the water inside the salt compartment it is extremely salty. The rinse aid is ok and we use the Tesco value tablets. I have also noticed that the element has a calcium build up on it. Surely if the water resevoir is very salty, how some I am getting all this calcium build up?

I have a feeling that there is solidified salt in the compartment, has anyone ever come across this and how did you fix it?

Thanks in advance.

Jeff