post_nav_link not showing up

I upgraded to 2.1 from 2.04 few days ago. I’m not sure that this issue is related to this upgrade but today i just observed that at the end of my index WP page where the post nav link should appear, now there’s nothing showing up. I looked into the source code of the index.php and all seems to be just fine, i also tried replacing that piece of code from a fresh 2.1 WP classic theme, and didn’t work. Also tried with the classic’s theme style file, again no result. And i can’t find where the problem comes from. What’s more strange is that i did the same upgrade on my other blog and it worked just fine.
Also on the “damaged” blog i have problems when i try to modify my blogroll links (url’s, images, descripsions) it just doesen’t save my changes, when i go back to edit a link it has the same old data. However i did mange to modify some links after a few tries, but i don’t think that’s normal.

Any suggestion related to my problems will be welcomed!
Thanks in advance
the blog url is curaj.net