Fix #237 get_instance() was being called in the output class before the CI_Controller exists.
diff --git a/system/core/Output.php b/system/core/Output.php
index 27a3a4b..0b708e1 100644
--- a/system/core/Output.php
+++ b/system/core/Output.php
@@ -214,7 +214,7 @@
 		global $BM, $CFG;
 
 		// Grab the super object if we can.
-		if (function_exists('get_instance'))
+		if (class_exists('CI_Controller'))
 		{
 			$CI =& get_instance();
 		}