Added fix for issue: https://github.com/EllisLab/CodeIgniter/issues/1277
diff --git a/system/helpers/download_helper.php b/system/helpers/download_helper.php
index 19192a1..18fe962 100644
--- a/system/helpers/download_helper.php
+++ b/system/helpers/download_helper.php
@@ -100,6 +100,9 @@
 			$x[count($x) - 1] = strtoupper($extension);
 			$filename = implode('.', $x);
 		}
+		
+		//Clean output buffer
+		ob_clean();
 
 		// Generate the server headers
 		header('Content-Type: '.$mime);