[Samba] File size differs

[CyberFox]

I have a peculiar problem on our office server, running Debian 3.0r2 with
Samba 2.2.3a-12.3.

Every user mounts his/her homedir as a mapped networkdrive, in which there are
links to the common directories.
If we save a file from within a program (like photoshop, flash) on the server
the size differs from the same file saved locally. When copied with FTP,
a filemanager or the windows explorer itself the size does not differ at all.
This problem only occurs when working on a WinXP workstation, not with Win98
(we do not have other OS's to check).
Also at home, where the configurations are the same (WinXP, Debian + Samba,
same versions), the problem does not exist, strangely enough.

All systems are without any viruses or firewalls.
I have experimented with configuration directives like:
- large readwrite	default: no, current: no
- read raw		default: yes, current: yes
- write raw		default: yes, current: yes
- nt smb support	default: yes, current: yes

It seems, after some tests, that files bigger than 64k do not differ in size.
This is only a suspicion though.

How to solve this?