[Samba] samba(-3.0.10) + Excel(2003), file locking issue?

[Rex Dieter]

Using samba-3.0.10(*) on RedHat Enterprise 3, and client WinXP boxes 
with Office 2003.  All servers and clients have synchronized clocks (ntp).

I open an excel file from a samba share, modify it, the *first* (and 
only first) time I save, Excel says:

The file 'foo.xls' may have been changed by another user since you last 
saved it.  In that case, what do you want:
O   Save a copy
O   Overwrite changes

Any ideas what's going on here?

-- Rex

(*) It happened with older version(s) too, but I thought I'd verify 
against the latest release