Added 'application/msexcel' to config/mimes.php for .xls files.
diff --git a/system/application/config/mimes.php b/system/application/config/mimes.php
index 10acfad..438f610 100644
--- a/system/application/config/mimes.php
+++ b/system/application/config/mimes.php
@@ -29,7 +29,7 @@
 				'smi'	=>	'application/smil',
 				'smil'	=>	'application/smil',
 				'mif'	=>	'application/vnd.mif',
-				'xls'	=>	array('application/excel', 'application/vnd.ms-excel'),
+				'xls'	=>	array('application/excel', 'application/vnd.ms-excel', 'application/msexcel'),
 				'ppt'	=>	array('application/powerpoint', 'application/vnd.ms-powerpoint'),
 				'wbxml'	=>	'application/wbxml',
 				'wmlc'	=>	'application/wmlc',