Index: wp-admin/includes/misc.php
===================================================================
--- wp-admin/includes/misc.php	(revision 16166)
+++ wp-admin/includes/misc.php	(working copy)
@@ -343,13 +343,16 @@
 
 		switch ( $map_option ) {
 			case 'edit_per_page':
-			case 'sites_network_per_page':
 			case 'users_per_page':
-			case 'users_network_per_page':
 			case 'edit_comments_per_page':
 			case 'upload_per_page':
 			case 'edit_tags_per_page':
 			case 'plugins_per_page':
+			// Multisite specific
+			case 'sites_network_per_page':
+			case 'users_network_per_page':
+			case 'plugins_network_per_page':
+			case 'themes_network_per_page':
 				$value = (int) $value;
 				if ( $value < 1 || $value > 999 )
 					return;
Index: wp-admin/network/themes.php
===================================================================
--- wp-admin/network/themes.php	(revision 16166)
+++ wp-admin/network/themes.php	(working copy)
@@ -66,7 +66,7 @@
 $wp_list_table->prepare_items();
 add_thickbox();
 
-add_screen_option( 'per_page', array('label' => _x( 'Themes', 'themes per page (screen options)' ), 'default' => 999) );
+add_screen_option( 'per_page', array('label' => _x( 'Themes', 'themes per page (screen options)' )) );
 
 add_contextual_help($current_screen, 
 	'<p>' . __('This screen enables and disables the inclusion of themes available to choose in the Appearance menu for each site. It does not activate or deactivate which theme a site is currently using.') . '</p>' . 
Index: wp-admin/plugins.php
===================================================================
--- wp-admin/plugins.php	(revision 16166)
+++ wp-admin/plugins.php	(working copy)
@@ -296,7 +296,7 @@
 wp_enqueue_script('plugin-install');
 add_thickbox();
 
-add_screen_option( 'per_page', array('label' => _x( 'Plugins', 'plugins per page (screen options)' ), 'default' => 999) );
+add_screen_option( 'per_page', array('label' => _x( 'Plugins', 'plugins per page (screen options)' )) );
 
 add_contextual_help($current_screen,
 	'<p>' . __('Plugins extend and expand the functionality of WordPress. Once a plugin is installed, you may activate it or deactivate it here.') . '</p>' .