If you do not maintain the washer, it will eventually have this problem. There are a few things that you can/should do in order to keep this issue from occuring. The easiest and most common would be to leave the door open after the wash cycle has completed and the washer is empty. Also, wiping the door and rubber gasket will help. You also should be draining the washer monthly and cleaning the filter which on LG's are locate on the front of the unit towards the bottom. It is also a good idea to drain the washer if you are going on vacation or not planning on using your washer for days at a time. Lastly, using a washer machine cleaner such as Affresh will go a long way. It's fairly cheap at only $8.99 which will include 3 tablets (3month supply). Use one tablet in a normal cycle or tub clean cycle once a month and you will greatly increase the chances of preventing the mold and mildew build-up.