Fixed upload issue reported by Valhallen and fixed by bubbafoley.
diff --git a/system/libraries/Upload.php b/system/libraries/Upload.php
index e15ea1b..2012fb3 100644
--- a/system/libraries/Upload.php
+++ b/system/libraries/Upload.php
@@ -951,7 +951,7 @@
 
 		if (count($this->mimes) == 0)
 		{
-			if (@require_once(APPPATH.'config/mimes'.EXT))
+			if (@require(APPPATH.'config/mimes'.EXT))
 			{
 				$this->mimes = $mimes;
 				unset($mimes);