I've got the same problem on another host (since I'm attempting to check out various hosting). My root site does not work (address.com, for example) but adding /index.php is the only way to get it to work. Not even a /index works, it must have the file extension. I can't log in, of course, because it's trying to go to a page without a file extension, thus I get a 500 Internal Server Error (same as I get when I try to visit the index without the file extension).
And yes, the .htaccess was uploaded.
My
guess is that mod_rewrite is disabled... though the tech support insists that
is on.