Index: wp-admin/users.php
===================================================================
--- wp-admin/users.php	(revision 6574)
+++ wp-admin/users.php	(working copy)
@@ -8,7 +8,7 @@
 $title = __('Users');
 $parent_file = 'users.php';
 
-$action = $_REQUEST['action'];
+$action = ( isset($_REQUEST['action']) ) ? $_REQUEST['action'] : '';
 $update = '';
 
 if ( empty($_POST) ) {
@@ -61,6 +61,8 @@
 				$searches[] = $col . " LIKE '%$this->search_term%'";
 			$search_sql .= implode(' OR ', $searches);
 			$search_sql .= ')';
+		} else {
+			$search_sql = '';
 		}
 		$this->query_from_where = "FROM $wpdb->users WHERE 1=1 $search_sql";
 
@@ -276,8 +278,11 @@
 	include('admin-header.php');
 
 	// Query the users
-	$wp_user_search = new WP_User_Search($_GET['usersearch'], $_GET['userspage']);
 
+	$usersearch = ( isset($_GET['usersearch']) ) ? $_GET['usersearch'] : null;
+	$userspage = ( isset($_GET['userspage']) ) ? $_GET['userspage'] : null;
+	$wp_user_search = new WP_User_Search($usersearch, $userspage);
+
 	// Make the user objects
 	foreach ( $wp_user_search->get_results() as $userid ) {
 		$tmp_user = new WP_User($userid);
@@ -320,7 +325,7 @@
 		}
 	endif; ?>
 
-<?php if ( is_wp_error( $errors ) ) : ?>
+<?php if ( ! empty($errors) && is_wp_error( $errors ) ) : ?>
 	<div class="error">
 		<ul>
 		<?php
@@ -429,7 +434,7 @@
 </div>
 
 <?php
-	if ( is_wp_error($add_user_errors) ) {
+	if ( ! empty($add_user_errors) && is_wp_error($add_user_errors) ) {
 		foreach ( array('user_login' => 'user_login', 'first_name' => 'user_firstname', 'last_name' => 'user_lastname', 'email' => 'user_email', 'url' => 'user_uri', 'role' => 'user_role') as $formpost => $var ) {
 			$var = 'new_' . $var;
 			$$var = attribute_escape(stripslashes($_POST[$formpost]));
@@ -441,7 +446,7 @@
 <div class="wrap">
 <h2 id="add-new-user"><?php _e('Add New User') ?></h2>
 
-<?php if ( is_wp_error( $add_user_errors ) ) : ?>
+<?php if ( ! empty($add_user_errors) && is_wp_error( $add_user_errors ) ) : ?>
 	<div class="error">
 		<?php
 			foreach ( $add_user_errors->get_error_messages() as $message )
@@ -464,23 +469,23 @@
 <table class="editform" width="100%" cellspacing="2" cellpadding="5">
 	<tr class="form-field form-required">
 		<th scope="row" width="33%"><?php _e('Username (required)') ?><input name="action" type="hidden" id="action" value="adduser" /></th>
-		<td width="66%"><input name="user_login" type="text" id="user_login" value="<?php echo $new_user_login; ?>" /></td>
+		<td width="66%"><input name="user_login" type="text" id="user_login" value="<?php echo ( ! empty($new_user_login) ) ? $new_user_login : ''; ?>" /></td>
 	</tr>
 	<tr class="form-field">
 		<th scope="row"><?php _e('First Name') ?> </th>
-		<td><input name="first_name" type="text" id="first_name" value="<?php echo $new_user_firstname; ?>" /></td>
+		<td><input name="first_name" type="text" id="first_name" value="<?php echo ( ! empty($new_user_firstname) ) ? $new_user_firstname : ''; ?>" /></td>
 	</tr>
 	<tr class="form-field">
 		<th scope="row"><?php _e('Last Name') ?> </th>
-		<td><input name="last_name" type="text" id="last_name" value="<?php echo $new_user_lastname; ?>" /></td>
+		<td><input name="last_name" type="text" id="last_name" value="<?php echo ( ! empty($new_user_lastname) ) ? $new_user_lastname : ''; ?>" /></td>
 	</tr>
 	<tr class="form-field form-required">
 		<th scope="row"><?php _e('E-mail (required)') ?></th>
-		<td><input name="email" type="text" id="email" value="<?php echo $new_user_email; ?>" /></td>
+		<td><input name="email" type="text" id="email" value="<?php echo ( ! empty($new_user_email) ) ? $new_user_email : ''; ?>" /></td>
 	</tr>
 	<tr class="form-field">
 		<th scope="row"><?php _e('Website') ?></th>
-		<td><input name="url" type="text" id="url" value="<?php echo $new_user_uri; ?>" /></td>
+		<td><input name="url" type="text" id="url" value="<?php echo ( ! empty($new_user_uri) ) ? $new_user_uri : ''; ?>" /></td>
 	</tr>
 
 <?php if ( apply_filters('show_password_fields', true) ) : ?>
@@ -496,7 +501,7 @@
 		<th scope="row"><?php _e('Role'); ?></th>
 		<td><select name="role" id="role">
 			<?php
-			if ( !$new_user_role )
+			if ( empty($new_user_role) )
 				$new_user_role = get_option('default_role');
 			wp_dropdown_roles($new_user_role);
 			?>