I can tell you 'how come', but I can't answer 'why'.
All the storyline dropdowns call on
siteadmin.keenspace.com/cgi-bin/dropdown.cgi to perform the redirect. This doesn't work due to the server move (siteadmin is being replaced, quite aptly, by schlockadmin).
On the index page tho' the dropdown calls
www.keenspace.com/cgi-bin/dropdown.cgi. That's on an older server and AutoKeen (which writes the dropdown form your text file) shouldn't be referring to it.
But it is, and it works. Go figure.

<B>Don't Panic.</B> - Hitch-Hikers Guide to the Galaxy, Isaiah 43.