I recently upgraded two of my blogs that were running on 2.1 to 2.6. Now I'm seeing the dreaded "categories missing" problem on both of them. Permalinks and everything else works fine. I don't know a lot about databases, I'm a graphic designer. I've been reading that I should have upgraded to 2.3 first, then moved on to 2.6. Well, it's too late, I've already installed 2.6. Will I do even more damage if I try to install 2.3 now and then install 2.6 again over that? What kind of process is involved in "downgrading?" If anyone has a tutorial or experience with this I would appreciate it.