Drupal seems to have a recurring problem where the file system just doesn't want to work. It's getting to the point where I'd suggest people to use custom solutions (or another CMS) instead. Given that, it's not surprising that downloads are broken on this site again, and until Rob and I get it fixed, if you're looking for any of the downloadable content (projects or article attachments), you'll just have to sit tight for a bit. Sorry!