I have 2 blogs, one 2.5.1, and one 2.2, and installed this in both of them. At first the categories on 2.2. looked strange in the column, but then they looked ok. I recently noticed that although the plugin has been great at showing related pages, the categories appear, but get a big error message from mysql when you click them! Here: http://www.donnabarstow.com/park_blog/.
Even worse, I've disabled YARPP, but and I still can't get the categories to work.
Same with my 2.5.1 blog. Except this blog also has tags, and now they are totally gone, although I can see them in my admin pages under manage, NONE show up next to each post. There are no categories in manage, or on the blog itself in the column. I deactivated the plugin, and still nothing is fixed.
I've never had a plugin make such a mess of my whole blog. What can I do now to fix everything and get my categories and tags back?