Summary: I can see all pages except the blog's home page. Refreshing the screen doesn't help.
The server has php version 4.4.2-1+b1 (FastCGI mode) and everything worked fine until I upgraded to Wordpress 2.1.3 and then tried to install Google Sitemap Generator plugin.
After hitting some problems including this one I decided to do a completely fresh install by deleting all WP files from the server (inc the plugin) and the database and then following instructions for a clean install.
I still just see a white screen :-(
What have I done wrong?