Empty Title and Contents When Editing Blog

I've posted my first blog entry on my newly installed v1.7.6 site. I was able to save my post several times, and bring it up again to edit it. But now when I try to edit it, both the title and the content areas are blank. I created another blog entry, and when I went back to edit the first one, it opened, but having tried since, it comes up blank again. The second post seems to be ok.

I'm doing the final testing before the site goes live, so this has got me worried. Can anyone tell me what the problem is?