WordPress 1.5.1 ruining my posts

Well I just upgraded from 1.5 to 1.5.1, and so far all it has managed to do is distort all my posts. It adds tags everywhere, tables, images, and two tags for actual places where there should be one. I never had this problem with WP1.5, is their a fix for this? Or should I consider unupgrading if that’s possible?

PS. I downloaded the latest stable release from the download section of this site.