Sounds like a blockage in the drain hose, or the drain pump has seized up. Sometimes, if you free the pump rotor off manually by turning it round a few times, it will startup when power is resumed. This can be attributed to rice or congealed fat in the pump. Sometimes, the pumps bearings leak, and the drain pump seizes up completely. Another common cause is under-sink drain assemblies where the DW hose is fed straight in to the drain. These are prone to fatty deposit build up (as the hot greasy drain fluid meets fresh cold water)
Hotpoint Man, February 2006