[Plugin: FeedWordPress] Error 500 on frontend

Hi everyone,
I designed a website feedwordpress-based,infact I need to show rss like wordpress post.
I have problem with this plugin that cause an Error 500 on frontend while backend is still navigable.
How can fix this this problem? I’ve just rebuild the entire website two times…

http://ww.wp.xz.cn/extend/plugins/feedwordpress/