Hi!
I have a blog-thingie called [url=http://fyrkant.net]fyrkant.net[/url]. The site is in swedish, so you probably won't understand that much.
But if you go to it you can see the nav-link at the very end, in swedish looking like this: " :: Nästa sida >>" (next page). My problem is that if you click that and go to the next page you only see a "<< Föregående sida :: " (previous page) -link and not another next page-link, which is weird because I have been using this script for about two years now, so there are posts enough to fill a helluva lot more than two pages... :)
Why does this happen? There should be some connection to the position of the "posts_nav_link"-tag, right?
I think it has something to do with your skin. I viewed page 5 using the custom skin:
http://fyrkant.net/?blog=3&page=1&disp=posts&paged=5&skin=custom
And both links were there. Compare the php code for the navlink in your skin to the code in the Custom skin.