Hello,
I am having the same problem as a previous commenter:
Advanced iFrame [resolved] Warning: Cannot modify header information - headers already sent
It seems to me that if the post is created before the autosave is created it works but once created you cannot edit the post.
I have deactivated the plugin and everything works fine until I reactivate it.
I love this plugin!
Thanks for creating and maintaining it.
Regards,
Eoghan