Problem: You installed with one of the default EE themes.  When you view your main page everything looks fine, but if you go to a page such as your comments page then the background images don’t appear.

Solution: The problem here has to do with the way the background images are specified in the accompanying CSS (located in the “weblog_css” Template by default).  By default, images are referenced similar to this:

The image is referenced with a relative path.  For the vast majority of people this works just fine.  Some people, however, may run into a problem where the images don’t appear on subpages.  In this case, you can change the CSS to refer to the images with an absolute path.  For instance:

Note that the period at the beginning of the path was removed.  You’ll need to make sure that the absolute path is correct with respect to your base site directory.