I've had my posts in categories and working fine on a new site, and use WP version 2.7.1. I renamed the uncategorized category to news so this was my default, several weeks ago. Everything has been working fine from then until today. This afternoon I go to make some changes to my site and all my posts have become "uncategorised".
I have tried to quick edit posts and select their correct category, but when I click update nothing changes. The same goes for posts I go into and change. When I edit the post, where a category is normally checked on the right hand side, these are all unchecked. I don't get any error message when I try to change the categories, they just don't update once I click update.
I created a new category, but I can't assign posts to that either, so I don't know what to try next. I can live without categories in the short term, but would like to fix this if possible.
The site is here.