samba - Nov 2003 - very odd behavior for concurrent file access in Samba3.0 with MS Word

Dear All ,
I am re-posting after a couple of weeks the following issue related to
MS Word and Samba 3.0 hoping that this time somebody could help me
unlock the mystery.  I have installed Samba 3.0 rpm on RH 9 and cannot
get past an elementary file lock issue such as opening a file through MS
WORD by multiple users from different MS workstations (w2k, XP,W98, etc)
in concurrent sessions. Nobody gets that sort of warning  "  ..test.doc
is already open by ...Do you want to make a copy?" . I tried every
lock/oplocks feature, still with no positive results (starting from
default settings, obviously).

Strangely, Powepoint, Excel react normally to the same test. I also
tried with other nics and switches , but I realized the network
infrastructure is not an issue. However reproducing the same samba rpm+
RH combination on a different machine (a laptop), the problem magically
disappears.
 It is very frustrating as I am supposed to make use of the server in
question; maybe there is something else to look for. 
Please help,

Thank you,
Cristian