I installed All-in-One Calendar on a test site that has no plugins and everything worked fine. Then I installed on a cloned test site with many plugins and got a fatal error message that cancelled the install. Despite this cancellation i had to ftp and delete All-in-One directory to regain control. I'm trying to narrow down the plugin that mights be causing the problem. Any hints would be appreciated. Here's the error message:
Fatal error: Ai1ec_Settings::get_instance() [ai1ec-settings.get-instance]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "Ai1ec_Settings" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition in [site url deleted from this post]/wp-content/plugins/all-in-one-event-calendar/app/model/class-ai1ec-settings.php on line 273.