[Samba] W2K3 Domain - Can't Connect to Share?

[Nolan Garrett]

I have a linux box, Samba 3.0.23a, that is joined to a W2K3 domain.  I
cannot connect to the "MP3s" share (all legal!) on this system - I can
connect to home directories and printers.  When I try to connect to MP3s
as any user on the domain, I get an Access is denied message, or it
prompts me for the username and password again.  I am using Winbind (if
that matters), so none of these accounts exist locally on the system.

Here is the applicable part of my smb.conf:
[MP3s]
        path = /home/samba/MP3s
;       writeable = no
        browseable = yes
        valid users = @"MASSIVEGEEK+Domain Users"
        writeable = yes

And here is the actual file permissions:
drwxrwx--- 93 root domain users 4096 Jul 14 18:54 MP3s

Any ideas here?  I've tried connecting from several different systems
(XP, 2003, Linux), with no luck.  Here is output from smbclient:

[root at mgprisvr ~]# smbclient //mggryphont.massivegeek.local/MP3s -U
MASSIVEGEEK\\mgwinxpvm1vpn -d 2
added interface ip=192.168.0.1 bcast=192.168.0.255 nmask=255.255.255.0
added interface ip=127.0.0.1 bcast=127.255.255.255 nmask=255.0.0.0
Password:
Domain=[MASSIVEGEEK] OS=[Unix] Server=[Samba 3.0.23a-1.fc5.1]
tree connect failed: NT_STATUS_ACCESS_DENIED

Thank you!

Nolan