As you know Google does not like duplicate content and if you notice your site suddenly having problems with rankings make sure no one is using your content. I have a client whose site was not doing well at all and he didn’t know why. It ends up that the copywriter he used took all of his content off of the net from other sites. So, he paid me to rewrite it all and he had a lot. I recommend Copyscape to all of my clients. With their services you can make sure no one has stolen your content. They offer a free service that is great, but they also offer a service and they offer Copysentry which automatically monitors the web for copies of your pages- $4.95 a month. Check out Copyscape today. You may be surprised at what you find.