Index: trunk/core/units/categories/categories_item.php
===================================================================
diff -u -r7635 -r7855
--- trunk/core/units/categories/categories_item.php	(.../categories_item.php)	(revision 7635)
+++ trunk/core/units/categories/categories_item.php	(.../categories_item.php)	(revision 7855)
@@ -75,7 +75,8 @@
 
 		function checkFilename()
 		{
-			if( !$this->GetDBField('AutomaticFilename') )
+			// System templates allow any characters in filename, because they may and will contain "/"
+			if( !$this->GetDBField('AutomaticFilename') && !$this->GetDBField('IsSystem'))
 			{
 				$filename = $this->GetDBField('Filename');
 				$this->SetDBField('Filename', $this->stripDisallowed($filename) );