My dishwasher won't stop bleeping !!!?

I have a diplomat dishwasher, it is used a lot !!! Yesterday i put washing-up liquid in it and it flooded out. Since then, it seems to start washing, then flicks to the rinse programme, stops, and starts bleeping. It does not stop until I open the door. Also for about 6 months now every 2nd or 3rd wash there seems to be a grit type substance sprayed on all my crocks. I have to wash things two or three times Any ideas????? Help !!!!