I think the screen shot should have been taken with the page a little below...
I am guessing that what is causing it is the "Extra info" section, where the selectors for the "show posts of the last X days", the "go to board" and the search box are all in the same table row. I think these should proably be reorganized so they are not all on the same row. Especially depending on the boards names, the "Go to..." could take a good deal of width.