Hotpoint Ultima Dishwasher?

When the water enters the metering tank it fills up, then empties into the dishwasher, this will repeat 3 or 4 times and then the dishwasher stops. I then have to remove the inlet hose at a stop valve to release an air lock and the washer continues. This happens each time the machine is at the filling stages within a cycle. It is a BF32 model.