If it's anything like my cooker and I think most cooker clocks are very similar to one another - when you do cleaning it's quite easy to set the delay timer by accident.
You may have set the oven to wait for 8 hours and cook for five minutes - or even the other way round - without realising it.
The Key says it's locked out on a timed programme. Cycling the electricity and resetting the clock always fixes it on our cooker - every couple of months or so.
Quite why they put this feature on cookers i don't know - timed cooking is perhaps as few as one in ten thousand and these timers cause no end of problems and cost silly-money to replace when they go wrong - it's marketing managers gone mad in my view - insisting on having sexy and unnecessary features on their products. They should, at a very minimum, be castigated.
Peccavi, February 2009