[Samba] Can't modify ms word files with samba 3.3

[François Legal]

Hello, 
I tried this week to upgrade my samba 3.2.4 (2 PDCs one trusting the
other) to samba 3.3.0 then samba 3.3.1, and apart from the problem
with winbindd and trusted domain, my users are not able to modify any
ms word document (excel does the same). 

You can open the file correctly, modify it, and when saving it, it
pops up "Access denied" 

If you try to save the file in the same directory with another name,
it does not work either (sam "access denied" message). 
I tried to set og level to 10, but could not find anything pointing
me to the right direction. 
Can anybody help ? 
François