Same problem - lights 2 and 4 (wash and drying) flashing and it emptied itself halfway through the cycle. Hotpoint repair man didn't have to ask any questions, came with new heater element and replaced it. My problem was limescale which caused the heater sensor to think there was a problem even though there wasn't, so if you live in hard water area, try repeated cycles with a limescale remover and see if that works - cheaper than a callout and a new element!
Petey, October 2009