Got this:

Error: Call to undefined method DateTime::getDateInformation() (0)
#0 /home/*****/www/applications/calendar/sources/Event/Event.php(363): IPS\calendar\_Event::_findOccurances()
#1 /home/*****/www/applications/calendar/sources/Event/Event.php(2131): IPS\calendar\_Event->findOccurrences()
#2 /home/*****/www/applications/calendar/modules/front/calendar/view.php(178): IPS\calendar\_Event::retrieveEvents()
#3 /home/*****/www/applications/calendar/modules/front/calendar/view.php(125): IPS\calendar\modules\front\calendar\_view->_viewMonth()
#4 /home/*****/www/system/Dispatcher/Controller.php(101): IPS\calendar\modules\front\calendar\_view->manage()
#5 /home/*****/www/system/Dispatcher/Dispatcher.php(153): IPS\Dispatcher\_Controller->execute()
#6 /home/*****/www/index.php(13): IPS\_Dispatcher->run()
#7 {main}

 

Can it be a corrupted calendar entry? 

Please upload a fresh set of files from your client area, and then get this again.