Dishwasher runs through the cycle but doesn't stop

Hi,
I've had my dishwasher for about 3 years and have had no problems but lately my dishwasher runs throuth the cycle and the electronic timer counts down the time. When it gets to 0 the dishwasher keeps running. I watch and when it gets to 0 I manually turn the dishwasher off. Tonight when I tried to start the dishwasher the lights came on but nothing happened. Do you think i need a new dishwasher??