Snap server 2200
I had the same problem - our logon scripts would map the Snap Server network drives on Vista machines.
After serveral hours of trying to make it work, I created a new admin local user on the Snap Server administration pages, and used that username and password when connecting to the snap server. So now I've manually mapped connections to the shares using not my domain credentials, but the local user from the snap server.
Apart from the inconvenience it all works fine an' dandy!