I have a login screen that I force to be ssl, so like this: https://www.foobar.com/login then after they login, they get moved to the homepage: https://www.foobar.com/dashba
Has your homepage got any flash on it that makes a subsequent request to your server? Or any Ajax loading of content?
Have you checked headers being sent from the server? In IE you can use Fiddler or in Firefox use the Live Headers addon. Check for any new cookies being set or the CAKEPHP cookie having a different value.