You started off right, but quickly delved into the world of wrong.
China has pegged their currency to ours, but they pegged it BELOW our currency(in order to make buying goods from China more attractive). How do you think they keep their currency "pegged" without manipulation? And it's no secret that China has been doing this for years, and the world has let it go on for years because small economies are allowed to do that sort of thing to grow, but generally large economies aren't allowed to directly manipulate currency to that degree.
When the dollar falls(through "free" market mechanisms, not "manipulation"), instead of allowing the Yuan to appreciate, or catch up to the falling dollar, China purposely devalues the Yuan(usually by buying more dollars). This causes inflation in China and gives them a false competitive advantage.
Here is a good read, from 2006, about China's currency manipulation and why/how it has violated international currency manipulation standards.
http://www.epi.org/publications/entry/pm116/