diff --git a/wp-admin/includes/ms.php b/wp-admin/includes/ms.php
index 1956b06f9..410df8daf 100644
--- a/wp-admin/includes/ms.php
+++ b/wp-admin/includes/ms.php
@@ -1218,7 +1218,7 @@ function show_post_thumbnail_warning() {
 		return;
 	}
 	$mu_media_buttons = get_site_option( 'mu_media_buttons', array() );
-	if ( !$mu_media_buttons[ 'image' ] && current_theme_supports( 'post-thumbnails' ) ) {
+	if ( empty($mu_media_buttons[ 'image' ]) && current_theme_supports( 'post-thumbnails' ) ) {
 		echo "<div id='update-nag'>" . sprintf( __( "Warning! The current theme supports post thumbnails. You must enable image uploads on <a href='%s'>the options page</a> for it to work." ), admin_url( 'ms-options.php' ) ) . "</div>";
 	}
 }
diff --git a/wp-admin/ms-admin.php b/wp-admin/ms-admin.php
index b62105704..a28848f63 100644
--- a/wp-admin/ms-admin.php
+++ b/wp-admin/ms-admin.php
@@ -21,8 +21,8 @@ global $wpdb;
 $c_users = $wpdb->get_var("SELECT COUNT(id) FROM {$wpdb->users}");
 $c_blogs = $wpdb->get_var("SELECT COUNT(blog_id) FROM {$wpdb->blogs}");
 
-$user_text = sprintf( __ngettext( '%s user', '%s users', $c_users ), number_format_i18n( $c_users ) );
-$blog_text = sprintf( __ngettext( '%s blog', '%s blogs', $c_blogs ), number_format_i18n( $c_blogs ) );
+$user_text = sprintf( _n( '%s user', '%s users', $c_users ), number_format_i18n( $c_users ) );
+$blog_text = sprintf( _n( '%s blog', '%s blogs', $c_blogs ), number_format_i18n( $c_blogs ) );
 
 $sentence = sprintf( __( 'You have %1$s and %2$s.' ), $blog_text, $user_text );
 $title = __( 'Site Admin' );
diff --git a/wp-admin/ms-sites.php b/wp-admin/ms-sites.php
index 279049836..9a516f12f 100644
--- a/wp-admin/ms-sites.php
+++ b/wp-admin/ms-sites.php
@@ -14,10 +14,10 @@ require_once('admin-header.php');
 if ( !is_super_admin() )
 	wp_die( __('You do not have permission to access this page.') );
 
-$id = intval( $_GET['id'] );
+$id = isset($_GET['id']) ? intval( $_GET['id'] ) : 0;
 $protocol = is_ssl() ? 'https://' : 'http://';
 
-if ( $_GET['updated'] == 'true' ) {
+if ( isset($_GET['updated']) && $_GET['updated'] == 'true' ) {
 	?>
 	<div id="message" class="updated fade"><p>
 		<?php
@@ -70,7 +70,9 @@ if ( $_GET['updated'] == 'true' ) {
 	<?php
 }
 
-switch ( $_GET['action'] ) {
+$action = isset($_GET['action']) ? $_GET['action'] : 'list';
+
+switch ( $action ) {
 	// Edit blog
 	case "editblog":
 		$blog_prefix = $wpdb->get_blog_prefix( $id );
@@ -309,6 +311,7 @@ switch ( $_GET['action'] ) {
 	break;
 
 	// List blogs
+	case 'list':
 	default:
 		$apage = ( isset($_GET['apage'] ) && intval( $_GET['apage'] ) ) ? absint( $_GET['apage'] ) : 1;
 		$num = ( isset($_GET['num'] ) && intval( $_GET['num'] ) ) ? absint( $_GET['num'] ) : 15;