Your description of your problem sounds exactly the same as what happened to ours recently. My housemate told me he cleared the drain to no avail. However after draining the dishwasher thoroughly, I removed a lot more muck from the drainage hole in the bottom of the dishwasher (from inside). I checked the pump was working (which was more complicated and time consuming) and checked that the draining hose was also clear, turned the thing back on and it worked perfectly again. My assumption is that if we had cleaned the drain regularly, we would not have had this problem.
David
May 2006