modified the new check for a callable controller method to be case-insensitive for backwards compatibility and consistent behavior between PHP 4 and 5.
diff --git a/system/codeigniter/CodeIgniter.php b/system/codeigniter/CodeIgniter.php
index d1ef965..866be35 100644
--- a/system/codeigniter/CodeIgniter.php
+++ b/system/codeigniter/CodeIgniter.php
@@ -216,7 +216,7 @@
 	{

 		// is_callable() returns TRUE on some versions of PHP 5 for private and protected

 		// methods, so we'll use this workaround for consistent behavior

-		if (! in_array($method, get_class_methods($CI)))

+		if (! in_array(strtolower($method), array_map('strtolower', get_class_methods($CI))))

 		{

 			show_404("{$class}/{$method}");

 		}