I tested all related posts plugins and are incompatible with the event calendar plugin.
I tested "WordPress Related Posts", "Related Posts by Zemanta", "YARPP", "Shareholic" and others.
If the event calendar plugin is disabled the related posts plugins work well.
If the related posts plugins are disabled the event calendar plugin works well.
The site works, I can read all posts and pages but I get blank page in the dashboard. So I need to delete the plugin by ftp.