Merge pull request #5659 from aanbar/validation_reset_data

Fix #5605
diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index 09ac920..1bd5549 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -584,7 +584,7 @@
 			{
 				if ($row['is_array'] === FALSE)
 				{
-					isset($_POST[$field]) && $_POST[$field] = $row['postdata'];
+					isset($_POST[$field]) && $_POST[$field] = is_array($row['postdata']) ? NULL : $row['postdata'];
 				}
 				else
 				{