I see that your Host is BlueHost and there was an old issue with the Cloudflare service that is bundled with BlueHost, but I am not sure if that is still an issue or not. This forum topic is dated: January 30, 2013 http://forum.ait-pro.com/forums/topic/cloudflare-cloudflare-htaccess-code/#post-1569 so this may not be an issue anymore, but then again it may be the problem.
Are you using Cloudflare?