Samba mounted subdirectories: ownerships damaged

The file server of our school has been "upgraded", presumebly to
Windows 2003.

I use Linux, mounting my file share with Samba. Since the the upgrade
all the subdirectories in my "share" get wrong uid/gid. I found out
that those uid/gid are the ones on that server. In end effect, I can
not read my own files.

This is how I do it. I can do any more debugging on the client side.
The server ofcourse is out-of-bounds for any "intruders" like me :-(

====================
- /etc/fstab:
//mustang/rtn /home/rtn/mustang smbfs
user,noauto,uid=1000,gid=100,username=rtn 0 0

- rtn@local$ mkdir ~/mustang

- suid-bit of smbmount is set

- rtn@local$ mount ~/mustang
Password:

- rtn@local$ ls -ld ~/mustang
drwxr-xr-x 1 rtn users 4096 2005-06-13 16:14 /home/rtn/mustang/

- rtn@local$ ls -l ~/mustang
drwx------ 1 10517 10000 0 2005-06-13 16:14 private
drwxr-sr-x 1 10517 10000 0 2005-06-02 17:31 public
drwx------ 1 10517 10000 0 2002-11-27 09:27 settings
drwxr-s--- 1 10517 1000 0 2005-05-30 08:15 www
^wrong! should be rtn:users 1000:100
=============

I've tried with Samba 3.0.10 (Slackware 10.1 original) and
self-compiled 3.0.14a.

This must be a known issue. Any clue?