Lack of theme support for custom menus is my guess. Try switching to the default twenty eleven theme and see if it works then.
There is a drop down menu in the theme, and it worked two days ago… but now i can’t get it to work – it keeps jumping back.
Now I’ve tried switching to twenty eleven theme, and it’s exactly the same problem… the pages in the menu still keeps jumping back as parent, when I save…
What can I do??
I got it to work – i just had to disable the add-ons from Microsoft Cooperation – and then the problem was gone!