Open Stack

I've just set up a Newton cloud (Ubuntu), and when I try to launch an 
instance in Horizon, I'm greeted with this:

Security group 64f28706-29df-44fa-9dbe-4f856d517a1c not found for 
project 1b9a6a9b5fc947a9892354fe8277690e. (HTTP 400) (Request-ID: 
req-281c6e94-3ade-4385-9a75-f72effc97ab5).

* The security group exists (it's "default")
* The project exists (it's "admin")
* I've also created a new user/tenant/security group, and it has the 
same problem.
* Logs in /var/log/keystone/ on the Keystone server say nothing.

At a loss on this one.

Thanks,

-Ken