Mine actually stopped draining properly. I removed the filter from the centre and cleaned it thoroughly. I also used a test tube brucsh to clean the openings leading away from the bottom of the drain and even blew some air down them using a straw!!! Everything started working again so I kept pouring clean water into the bottom of the dishwasher and starting a cycle so it drained through. This seemed to clean the whole system out and lose the smells!
Also, have you run your finger or a cloth underneath the door from the inside? - Ours had loads of smelly scum in it.
Finally you can take the filter apart and there is often scum in there.
I have no idea if this will help you!!
Neil Phillips, July 2005