Manually disabling URL rewriting
If iZeit is installed on a server running Apache with the mod_rewrite module installed, URLs will be rewritten by default. This means instead of seeing http://www.yourdomain.com/calendar/index.php?act=manage&date=177872689&type=extended, you'll see a nicer version such as http://www.yourdomain.com/calendar/manage/extended.
This can sometimes cause problems with certain server configurations, so it may be necessary to disable it.
If you experience this problem, access the control panel by going to http://www.yourdomain.com/calendar/index.php?act=admin&page=calsetup, replacing /calendar/ with the path to your iZeit installation. Once you've logged in, scroll down to the URL Rewriting section and set it to disabled. Save the form and go back to wherever you installed iZeit.
URL rewriting should now be disabled.