I will download, install and test the All-in-One Event Calendar plugin and see if I can duplicate the same problem on my test site. It looks like All-in-One Event Calendar plugin has had issues/problems in the past, but the most recent reviews by folks are very good. So it looks like a lot of the older/previous issues/problems in that plugin have been fixed.
UPDATE: The All-in-One Event Calendar plugin has been tested with BPS Pro and there were no problems, issues or conflicts found with the All-in-One Event Calendar plugin. So the site crash problem is not related to or being caused by the All-in-One Event Calendar plugin and is/was caused by something else. If you are using a caching plugin that uses htaccess code (W3TC, WP Super Cache, etc) then make sure you have the most current/correct htaccess code for your caching plugin added to BPS Root Custom Code and then re-run the BPS Pro Wizards on this website.