I'm going to guess this is the same problem which causes the E90 fault on this family of machines; namely the loose connections on the 5-way blue cable between the front panel and the motor controller inside. The light by the on/off switch works directly off the mains, not off the supply to the front panel circuit board.
Open the lid (two screw bolts at top rear of machine, slide lid back). At top front, there are two bolts holding the panel on, and there are also two screws hidden behind the soap tray, plus a load of clips across the top. You'll need to dismantle the connectors on the blue cable and use some pliers to tighten the contacts up.
Thanks to Jason for this tip!
Colin., November 2004