CreateDC fails on an independent display

Hello everyone,

I have Vista Ultimate 64 bit with 2 graphics cards. The second card
should be an independent display (not part of the desktop), and
shouldn't have a monitor attached. However, I still need to create a
device context on it.
The problem is that CreateDC fails on the second display with
ERROR_DEVICE_NOT_READY.
On XP the call to CreateDC succeeds.
Why is this and how can this be worked around?

Thanks.


--
eigers