problems getting samba to work

[Zachariah Baum]

I've set up home directories with Samba thusly in the config file:

[homes]
   user = %S
   comment = Home Directories
   browseable = yes
   writable = yes

with my global values:
[global]
   user=zack
   workgroup = STUDIO
   browseable = yes
   locking = yes
   lock directory = /usr/local/samba/var/locks
   share modes = yes
   socket options = TCP_NODELAY
   os level = 0
   preferred master = no
   domain master = no
   local master = no
   wins support = no
   wins server =

   preserve case = yes
   short preserve case = yes

When I connect with smbclient from a machine other than the server that's
  running smbd, I can connect with the commandline:
    smbclient '\\Arkham\zack' -U zack
  although the prompt says "connected as guest security=share", which seems
  wrong, since I tried connecting as "zack".
Anyway, when I try connecting via NT, I get the list of shared directories OK,
  and the "zack" folder appears, but when I double click on it, type in my name
  and password, I get the message:
    \\Arkham\zack is not accessible.
    The account is not authorized to login from this station.
I'm running debugging levels 2 on nmbd, and 5 on smbd, and neither show any new
  output when I try to connect to the "zack" folder.
My NT machine that I'm connecting from is called "control_tower".
The permissions on my home directory are 755, owned by "zack".

Any ideas?
Zachariah