Removed closing PHP tags, replaced with a comment block identifying the end of the file
diff --git a/system/libraries/Trackback.php b/system/libraries/Trackback.php
index 3e1c202..41ac5fc 100644
--- a/system/libraries/Trackback.php
+++ b/system/libraries/Trackback.php
@@ -545,4 +545,6 @@
 

 }

 // END Trackback Class

-?>
\ No newline at end of file
+
+/* End of file Trackback.php */
+/* Location: ./system/libraries/Trackback.php */
\ No newline at end of file