self-hosted WP 2.8.4, pro-sense blue theme.
I installed Search API, trying to improve the search tool. It didn't seem to work.
So I backed-out (de-activated) all the Search API plug-ins, and deleted them, reverting to the default search - still, it's broken. It may have been broken before installing Search API.
My preference would be use to use Search API and the MySQL Fulltext search capability, but right now, search isn't working in any form.