On 4 or 5 occasions now when we start the dishwasher, it will begin to fill and then stop after a few seconds. You can hear the timer ticking but nothing is happenning. On almost each occasion we have fiddled with the rotary switch for a little bit (cycling it through several times) and the dishwasher has begun to operate normally and then will work fine for several days. The heating element still gets hot but no washing or rinsing occurs. Any ideas?

I should also say that in addition to cycling the timer the door was openned and closed.