What kind is it? Lots of articles on Bosch dishwashers having a smell. If it's a Bosch, it may be because it's not corrected correctly, they need to have the drain line running precisely or they don't drain right. A quick fix may be to run a cup of vinegar, that has worked for a few people if the problem is minor.

Here is a link that might be useful: Smelly dishwasher

Have you cleaned out the filter? If you have one. I have a bosch and didn't know the filter removed for several months.

Below is a link to a google search and lists several Gardenweb threads about smelly dishwashers.

Here is a link that might be useful: smelly dw