Got a strange one here.
Whenever I search for a post in the Manage screen of the Admin section, there are no hits, even when the title of an existing post contains the search query. It doesn't matter what post I search for, I consequently get zero hits when I use the search function.
The searchform on the frontend however does give results to a query, so this works fine.
I've tried deleting and reuploading the wp-admin and wp-includes folders, but to no avail.
Anyone have any idea what could be the problem here?