Not sure if anyone has had this issue - a bug I've come across on a multi-site instance of WordPress 3.4.1 using Events Manager 5.2.3...
Whenever I save Settings for Events Manager, my selected "Events page" (Settings > Pages > Event List/Archives) throws a 404.
I tried resetting permalinks, changing the selected page and the template, and also enabling the default Twenty Eleven theme to ensure this wasn't a theme issue, but I was still getting a 404.
I temporarily resolved the issue by changing the slug of the desired page, but every time I saved settings in Events Manager I got the same issue, and would have to change the slug again - however, I noticed that the page was also a child page (not top level parent) - I set up a test with a top level parent page and that seemed to work fine. Is this is an issue with setting the "Events page" to a child page, perhaps?
Thought this might help out anyone else who is having similar issues, and give the plugin devs a heads-up.