If you own a Dyson DC25 and haven't replaced or cleaned the filters, then check out this video. It's important to clean the filter on your vacuum cleaner because not only does it help to keep dust and other particles out of your motor, it also makes sure that none of that stuff is spwed back out onto your floor.
This tutorial will show you how to locate, remove, and clean both filters to your machine. It's a pretty easy fix and will take no time to complete. So check it out, good luck, and enjoy!