As the title says, the BBPress forum is full-width under the left sidebar, and then the right sidebar is all spread out underneath it. The default is left and right sidebar layout. This is on a new test site, and the problem occurred the update before last (it was fine before that). This last update did not resolve it.
Here is a link: http://reaching-out.sandpointadventureguide.com/forums/
You can see how it is supposed to look by navigating to the home page.