Hi alexbchalmers,
This is Neo Zhu from Office365 support. Office365 and live account provide different service scope for the users and also use the different storage for the service data. Once we use a STMP address which was/is live service account, , it will make a lot of problems for the applications on Windows8.
For this case, I would like you can use a pure live account (like @live.com , @hotmail.com) for the login account of Windows 8 system.
Thanks, Neo Zhu