This is my strange issue.
Tried also with a fresh WP install (2.8.5) on different servers.
1. I use Facebook Connect (well configured) and WP-PageNavi adding the PageNavi code on my page.
2. Thank I change the useragent of my browser to Googlebot (also with a plugin) and than I get a blank page instead of my site. Google confirm this by removing the site from the directory. Everything is ok if I browse the site normally.
Any idea? Sorry for my english