Why can't I copy office "owner files" from XP but can from Win7 RC

Hi all,

Using the same account/password from different computers I noticed that I
can't copy office "owner files" (starting with ~$ as explained here :

When a previously saved file is opened for editing, for printing, or for
review, Word creates a temporary file that has a .doc file name extension.
This file name extension begins with a tilde (~) that is followed by a dollar
sign ($) that is followed by the remainder of the original file name. This
temporary file holds the logon name of person who opens the file. This
temporary file is called the "owner file."
)

from Windows XP computers but can do it frmo Windows 7 RC computers.

Any insight would be greatly appreciated, thanks !