Probably piece of glass, china, bone etc jammed in the drain pump. You can access the pump impellor from inside the machine. Remove the filter tray and filter sleeve, bail out the water and you will see a small cover down in the sump left hand side remove the ONE screw holding it and note which hole it came out of .(there are 2 holes only one screw) remove this cover you will see pump impellor and clean it out also look under it If not this then blockage at sink connection. Or could be faulty pump.
Kenjo
April 2012