Ian, It sounds very much like my problem. Fortunately I was able to see the flooding and stop the machine, which stop the flood of water. It thus may be that in my case the valve is OK but the water level sensor is faulty and the pump is not working. I just received a new pump and will take the thing apart this weekend.
In your case it seem the problem was intermittent but in my case it flooded twice.
I will report my experience
thanks a lot for sharing your experience.
SM2K 278 Boston