Index: wp-includes/class-simplepie.php
===================================================================
--- wp-includes/class-simplepie.php	(revision 16695)
+++ wp-includes/class-simplepie.php	(working copy)
@@ -1831,7 +1831,7 @@
 	}
 
 	/**
-	 * Return the error message for the occured error
+	 * Return the error message for the occurred error
 	 *
 	 * @access public
 	 * @return string Error message
Index: wp-app.php
===================================================================
--- wp-app.php	(revision 16695)
+++ wp-app.php	(working copy)
@@ -712,7 +712,7 @@
 		$filetype = wp_check_filetype($location);
 
 		if ( !isset($location) || 'attachment' != $entry['post_type'] || empty($filetype['ext']) )
-			$this->internal_error(__('Error ocurred while accessing post metadata for file location.'));
+			$this->internal_error(__('Error occurred while accessing post metadata for file location.'));
 
 		// delete file
 		@unlink($location);
@@ -749,7 +749,7 @@
 		$filetype = wp_check_filetype($location);
 
 		if ( !isset($location) || 'attachment' != $entry['post_type'] || empty($filetype['ext']) )
-			$this->internal_error(__('Error ocurred while accessing post metadata for file location.'));
+			$this->internal_error(__('Error occurred while accessing post metadata for file location.'));
 
 		status_header('200');
 		header('Content-Type: ' . $entry['post_mime_type']);
@@ -801,7 +801,7 @@
 		$location = "{$upload_dir['basedir']}/{$location}";
 
 		if (!isset($location) || 'attachment' != $entry['post_type'] || empty($filetype['ext']))
-			$this->internal_error(__('Error ocurred while accessing post metadata for file location.'));
+			$this->internal_error(__('Error occurred while accessing post metadata for file location.'));
 
 		$fp = fopen("php://input", "rb");
 		$localfp = fopen($location, "w+");
Index: wp-admin/admin-ajax.php
===================================================================
--- wp-admin/admin-ajax.php	(revision 16695)
+++ wp-admin/admin-ajax.php	(working copy)
@@ -508,7 +508,7 @@
 	$tag = wp_insert_term($_POST['tag-name'], $taxonomy, $_POST );
 
 	if ( !$tag || is_wp_error($tag) || (!$tag = get_term( $tag['term_id'], $taxonomy )) ) {
-		$message = __('An error has occured. Please reload the page and try again.');
+		$message = __('An error has occurred. Please reload the page and try again.');
 		if ( is_wp_error($tag) && $tag->get_error_message() )
 			$message = $tag->get_error_message();
 
@@ -1343,7 +1343,7 @@
 	$sidebar_id = $_POST['sidebar'];
 	$multi_number = !empty($_POST['multi_number']) ? (int) $_POST['multi_number'] : 0;
 	$settings = isset($_POST['widget-' . $id_base]) && is_array($_POST['widget-' . $id_base]) ? $_POST['widget-' . $id_base] : false;
-	$error = '<p>' . __('An error has occured. Please reload the page and try again.') . '</p>';
+	$error = '<p>' . __('An error has occurred. Please reload the page and try again.') . '</p>';
 
 	$sidebars = wp_get_sidebars_widgets();
 	$sidebar = isset($sidebars[$sidebar_id]) ? $sidebars[$sidebar_id] : array();
Index: wp-admin/includes/class-wp-upgrader.php
===================================================================
--- wp-admin/includes/class-wp-upgrader.php	(revision 16695)
+++ wp-admin/includes/class-wp-upgrader.php	(working copy)
@@ -1081,7 +1081,7 @@
 
 	function add_strings() {
 		$this->upgrader->strings['skin_upgrade_start'] = __('The update process is starting. This process may take a while on some hosts, so please be patient.');
-		$this->upgrader->strings['skin_update_failed_error'] = __('An error occured while updating %1$s: <strong>%2$s</strong>.');
+		$this->upgrader->strings['skin_update_failed_error'] = __('An error occurred while updating %1$s: <strong>%2$s</strong>.');
 		$this->upgrader->strings['skin_update_failed'] = __('The update of %1$s failed.');
 		$this->upgrader->strings['skin_update_successful'] = __('%1$s updated successfully.').' <a onclick="%2$s" href="#" class="hide-if-no-js"><span>'.__('Show Details').'</span><span class="hidden">'.__('Hide Details').'</span>.</a>';
 		$this->upgrader->strings['skin_upgrade_end'] = __('All updates have been completed.');
Index: wp-admin/includes/theme.php
===================================================================
--- wp-admin/includes/theme.php	(revision 16695)
+++ wp-admin/includes/theme.php	(working copy)
@@ -389,11 +389,11 @@
 	if ( ! $res ) {
 		$request = wp_remote_post('http://api.wordpress.org/themes/info/1.0/', array( 'body' => array('action' => $action, 'request' => serialize($args))) );
 		if ( is_wp_error($request) ) {
-			$res = new WP_Error('themes_api_failed', __('An Unexpected HTTP Error occured during the API request.</p> <p><a href="?" onclick="document.location.reload(); return false;">Try again</a>'), $request->get_error_message() );
+			$res = new WP_Error('themes_api_failed', __('An Unexpected HTTP Error occurred during the API request.</p> <p><a href="?" onclick="document.location.reload(); return false;">Try again</a>'), $request->get_error_message() );
 		} else {
 			$res = unserialize($request['body']);
 			if ( ! $res )
-			$res = new WP_Error('themes_api_failed', __('An unknown error occured'), $request['body']);
+			$res = new WP_Error('themes_api_failed', __('An unknown error occurred'), $request['body']);
 		}
 	}
 	//var_dump(array($args, $res));