I am having the same problem. It seems to occur regularly – maybe half of the time. This is the error message:
Fatal error: GCE_Display::get_event_days(): The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "GCE_Event" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition in /home/content/p3pnexwpnas06_data03/79/2400579/html/wp-content/plugins/google-calendar-events/includes/class-gce-display.php on line 61
