That's what I'm using Zentyal 5.1 Development Edition. How did you upgrade to 6.0.1 ?
My configuration is as follows:
* no shared folders or recycle bins (GUI > File Sharing > Shared Folders)
* Default User Quota disabled from user templates (GUI > Users & Computers > User template)
* Quota disabled for user (GUI > Users & Computers > Manage > User (kaipee) > User quota )
I am assuming that since I have authenticated using the same account on both Linux and Windows machines, this is forced somehow to allow for a home directory for Linux user accounts?