As aynaco said, there is a conflict with the newest versions of AI1EC and W3 Total Cache. Just rename both of these plugin folders to deactivate them. Then uninstall W3TC as it is not necessary to the operation of your site, and re-activate AI1EC. Maybe they’ll play together better later on, but for now, it’s a no go. Personally, I haven’t noticed any performance gain from using W3TC anyway. Why is it so dang popular?
