Index: wp-admin/includes/misc.php
===================================================================
--- wp-admin/includes/misc.php	(revision 21877)
+++ wp-admin/includes/misc.php	(working copy)
@@ -325,7 +325,7 @@
 		$option = $_POST['wp_screen_options']['option'];
 		$value = $_POST['wp_screen_options']['value'];
 
-		if ( !preg_match( '/^[a-z_-]+$/', $option ) )
+		if ( $option != sanitize_key( $option ) )
 			return;
 
 		$map_option = $option;