RSS feeds return no posts after 2.5.1 upgrade – help!

I’ve upgraded 7 different blogs from WP 2.5 to WP 2.5.1 .

Every single blog’s RSS feed returns no posts. i.e. wp-rss2.php and wp-rss.php returns nothing. The posts are still there in the database and on the blog itself, so I know there’s content, just no reflectio in rss feed.

However, the simple if I type in http://www.smallbizpod.co.uk/feed rather than http://www.smallbizpod.co.uk/wp-rss2.php all works fine.

What’s going on?

Alex