samba - Jan 2003 - 8-bit characters in windows login

Hi,

I'm having a severe problem with the 2.2.7 version of samba. We have 
Windows users with "umlaut" characters (???) in their names. Now I
find
that obviously the login name sent by windows is truncated at the first 
such character (user is "Horst-G?nther Barzik"):

[2003/01/20 09:57:26, 10] lib/util.c:dump_data(1539)
  [030] 48 6F 72 73 74 2D 47 81  6E 74 68 65 72 20 42 61  Horst-G. nther Ba

and later:

[2003/01/20 09:57:26, 10] lib/username.c:user_in_list(460)
  user_in_list: checking user |Horst-G| against |administrator|

So "Horst-G?nther Barzik" becomes "Horst-G".

Can anybody help?

Thanks

    Michael