Howdy shawntarlo,
Thank you for posting! Frequently this is the result of improperly designed theme. Often times the theme author is using a non-standard way of detecting if this is a 404 page, instead of the method WordPress recommends which is using the is_404() function. For instance, sometimes theme authors will detect if the current page has 0 posts, and then assume that if there are 0 then this should be a 404 page. Well on some events pages, like a month view with no events, it will be 0. But, this should not be a 404 page as we are still serving content.
If disabling the theme and using the 2012 one instead fixes the problem, then you should get with your theme author and have them fix the issue.
Please let me know if you have further questions, or if disabling the theme did not fix it. Thanks!
Keidrych, if your issue is completely identical then my above comments would apply to you as well. If there is any difference please open a new topic, that will allow us to address your problem specifically. Thanks!
– Brook