drews

markus_b: I just discovered that the 404 problem has been resolved in the WordPress Trac. Seems to be an issue with static home pages, so this might solve your other problem as well.

Here’s the fix if you can’t wait until they implement the bug error:

Change line 922 of wp-includes/query.php from this:
if ( ('page' != get_option('show_on_front') ) || ( $reqpage != get_option('page_for_posts') ) ) {

to this:

if ( ('page' != get_option('show_on_front') ) || ( $reqpage !== get_option('page_for_posts') ) ) {

(Note the second part of the if statement changes from != to !==)