Dishwasher won't drain and is leaking water onto the floor?

I have a Kenmore Ultra wash (came with the house, no manual available). Last night I heard a dripping sound while it was running, and looked over to see water leaking out both bottom sides onto my floor. I stopped the dishwasher and found water standing in the bottom. I pushed the cancel/drain button, which started what sounded like another washing cycle. I let the dishes dry overnight and tried the cancel/drain button again, but after the cycle, my dishes were wet and the bottom of the washer was still filled with water. I never, ever put a dish in the dishwasher before cleaning it very thoroughly first, so I don't think anything is clogged. Suggestions??