[Samba] Why can not backup in Samba3.0.25?

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Dear all:
How do you do?I am now using the Samba3.0.25 as the file server.When I
backup files from the Vista and Win2003 to the Samba Server.(Notice:I use the
backup
function of the Windows itself,not just copy files commonly.)It can not
proceed!But it is sucessful when in WinXP.
    Why ?Please help me.
    Many thanks to you.

                                  yours Jian Liang