hi,
in case of entry-errors wp_die() is called, wich is located in wp-includes/functions.php. This function creates an error page with an header 500. This causes IE to forward to an internal error-page.
Using WP 2.6.3 i just set this line (1800) into comments: status_header( 500 );
Now the error Page is responded with a header 200 ok, and IE displays it. Did not find an better way…
regards, wende from Munich, Germany