This could be the sump of the dishwasher full of water, what happens is over time water leaks into the bottom of the dishwasher usually because the food strainer is not emptied regularly, when this happens the machine will either show errors in the front lights or just not work at all, unplug the machine from the mains, pull it into the middle of the kitchen get some towels and lay them behind the machine and tuck them under as well, now tilt the machine back at least 45 degrees, now quite a bit of water show be coming out, once its all out mop up the floor and push your machine back into its home and leave for a day so it can dry out, then it should start and run with no probs, but remember to empty the food strainer in the base of the machine regularly.
Gary, July 2007