When you open the door, does the drum continue to tumble?
If so, the door micro switch is buggered or it's jammed full of fluff.
If the drum does NOT continue to tumble but the heater element stays on, it sounds like an insulation fault. Past experience tells me that the wire harness to the bottom thermostat has rubbed against the drum, and is causing an electrical insulation fault. Simply repair and insulate the wire from the drum / drum support bar.
matt, September 2007