The question really is how did you get the first version!

Gotta be a css issue, or at least I *think* it will be there. In any case I would grab a fresh zip from the downloads page, unzip it on my PC, delete the skins_adm/ folder from my server, then upload the new one I just unzipped. Then do a CTRL refresh on the browser.

The first one occurred when I upgraded a blog to 2.3; the latter, "normal" one was from a fresh install.

Your advice fixed it!