If I try to modify the user's object in the nwadmin, then I get an error

"Modifying object properties failed
NWDSModifyObject returned -608"

Although the message says "Modifying object properties failed" the modify
will be accepted.

And there is an other problem, but I think both of them has tha same reason.
So, the other problem is when I try to start a mail server (niagara mail
server), I got an eorror message again (when it is trying to log in...)
which says:

"NWDS Login failed, error code = -602."

That's all.

I've got 2 nw6sp5 and 2 nw6.5sp3 servers, and the timesync is ok.