[Samba] group problems on Mac OS X

[Anthony A. D. Talltree]

Server:  SunOS 5.8 running, I believe, Samba 2.0.6 -- at least,  log.nmb says:
	 Netbios nameserver version 2.0.6 started.

Client:	M$WXP - everything works fine, perhaps because it has no concept
of file ownership groups

Client: Mac OS X 10.3.2, running the bundled Samba

I have a number of shares defined on the server, including one for / so
that I can get to anything on the machine with one mount:

[slash]
   path = /
   browseable = yes
   writable = yes
   valid users = aad

On the server:
 <=>lovecraft<=>id
uid=5001(aad) gid=5000(overlay)

On the OS X client:

[dagon:~/scratch] aad% id
uid=502(aad) gid=502(aad) groups=502(aad), 80(admin), 5000(overlay), 2147483647

I can't find a consistent way to mount this share at start up, but this
forum problably isn't the place to persue that.  The issue is that once
I do get it mounted, I have problems when moving files.  For some
reason, the gid of any of my files that are across the mount shows up as
4294967294:

[dagon:~/scratch] aad% touch
/private/var/automount/Network/TALLTREE/LOVECRAFT/slash/tmp/test

<=>lovecraft<=>ls -lg /tmp/test
-rwxr--r--   1 aad      overlay         0 Jan  1 18:56 test*

[dagon:~/scratch] aad% ls -lg
/private/var/automount/Network/TALLTREE/LOVECRAFT/slash/tmp/test
-rwx------  1 aad  nobody  0  1 Jan 18:59
/private/var/automount/Network/TALLTREE/LOVECRAFT/slash/tmp/test
[dagon:~/scratch] aad% mv
/private/var/automount/Network/TALLTREE/LOVECRAFT/slash/tmp/test .
mv: ./test: set owner/group (was: 502/4294967294): Operation not permitted
[dagon:~/scratch] aad% 

I created the "overlay" group on the OSX client via netinfo and added
myself to it.  The output of id above shows that it appears to be there
correctly.  The Samba mount appears to handle the uid just fine by
looking up "aad" appropriately at both ends, but where the heck is it
getting this wacky gid?  Do I need to upgrade Samba on the server?  Is
the uid disparity between the two systems causing a problem?

Thanks for any help.