[Samba] same time file access problem

[skuda]

hi, i have a problem with my samba 2.2.3a. my machine is a Debian woody
with kernel 2.4.18 and the filesystem of the shared disk is reiserfs.
well my problem is what when in a program that uses the share two people
save the changes at the same time, one of the two changes its loosed, in
my smb.conf is a line that i dont know what is. kernel oplocks = no, but
i dont know if it is the problem or is other problem, if i use the same
program shared on a windows 98 machine we doesnt have the problem,
thanks by the help and sorry for my poor english