How to fix problem of enclosures auto deleting:

    Comment out these lines, in wp-includes/functions.php (add the /*
    and */)

	/* foreach ( $pung as $link_test ) {
		if ( ! in_array( $link_test, $post_links_temp ) ) { // link no longer in post
			$mids = $wpdb->get_col( $wpdb->prepare("SELECT meta_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE (%s)", $post_ID, like_escape( $link_test ) . '%') );
			foreach ( $mids as $mid )
				delete_metadata_by_mid( 'post', $mid );
		}
	} */