My third party web host recently installed wordpress on a subdirectory (xyz.com/wordpress). I later changed my mind and manually moved the files to the root directory so that the blog would show up on my site's home page.
Unfortunately, I didn't do a good job. Xyz.com does show the blog, but the style and formatting is off. And all of the web addresses associated with the hyper links on my site reference some variant of xyz.com/wordpress... Since the /wordpress subdirectory no longer exists, none of the links work.