[Samba] Windows Vista Logging into SAMBA PDC

[James]

Hey guys i have a Samba PDC setup with LDAP and i've got windows XP 
clients logging into it fine.
I originally had version 3.0.24etch for debian installed but i upgraded 
my samba version to 3.0.26 to see if it'd iron out but that didn't work.

I can JOIN the samba domain but i can't LOGIN to the domain with a user.
I get an RPC failure on the login screen for vista
I login fine from windows xp clients.

Any suggestions for me?
Thanks in advance