My gallery for this particular post has a lot of images in it. 379 actually. When I try to change the sort order from ascending to descending and click save all changes I get a 403 forbidden error saying that i don't have permissions for wp-admin/media-upload.php. I've checked permissions and they are fine.
This option works fine on other galleries with less images as well.
I couldn't find anything with a google search on the topic.