The reason why it isn’t showing any error messages is probably because of security settings in PHP’s configuration.
I’m getting a major problem as well (upgrading from 2.0.7 to 2.1). Fortunately, I know what the error message is:
Fatal error: Call to undefined function: add_filter() in (snip)public_html/blog/wp-includes/default-filters.php on line 4
Which is simple enough: the add_filters function is missing. Without the right settings in PHP, though, I would be staring at a blank screen site-wide just like gezellig-girl is seeing.
The next step is to re-download WP and see if I just downloaded a bad copy.
