I had exactly the same problem as described above but finally got rid of it: Having a look at the MySQL table ‘wp_posts’ it seemed as the ‘Homepage’ entry had a wrong ‘post_parent’ attribute. Actually, it was pointing to a page which didn’t exist. After changing this value back to ‘0’ all the dropdown options reappeared instantly.
Don’t know whether this was a very specific problem but maybe this helps some of you facing similar problems.
Cheers.
