Problem with download: error 403

I’ve uploaded all files via FTP and all worked fine but I can’t download any file from certain moment. Browser returns “403: Forbidden – You don’t have permission to access” I have tried set chmod to 777 (all files and folders) but it doesn’t helped. And of course, each file has permission set for “All”.

http://ww.wp.xz.cn/plugins/wp-filebase/