My dwf64sse smeg dishwasher keeps stopping?

My dishwasher keeps stopping mid cycle on programme 5 & 7 but fully works on the rapid programme 3. Have cleaned the inside thoroughly and checked that the water is draining properly. It seems to wash okay but stops before it finishes draining. when I open the door it is full of steam and the water is not drained. In order to drain it I have to advance to the next step by keeping the start button pressed down.

CAT
January 2010