WordPress version: 3.0.1
Symptoms:
1. The content of my posts were not editable. When I pushed “update” wordpress returned a “post edited” message, but the content did not change. I could change categories, tags, publish date, etc. but not the content of the post.
Later:
2. All the posts disappeared. The home page displayed a 404 error and when I went into wp-admin, it showed that I had 0 posts.
Solution:
Open up phpmyadmin and run “repair table wp_posts”