Vista - Send files to web folder, suppress password request (passthrough I

Hi,

we have a SharePoint form library mapped to a local PC as a network drive
(web folder via the WebDAV service). I wrote a script to generate compatible
forms and send them to the library with the following (relevant) piece of
code:

For Each objfile in objFolder.Files

objfile.Move WebFolder & "\" & objfile.name

WScript.Sleep 1000 ' to avoid starting dozens of workflows at once
Next

Unfortunately, an attempt to access the web folder pops up a logon&password
request. Once the user's password is entered, the popup goes away until next
logon.

I'm looking for a way to suppress this popup permanently, so the script can
run without human intervention.

Hints:
ProblemOS: Windows Server 2003 SP2.
The same script runs without problems on an XP (SP2) machine.

The user is an admin account on the local PC and has Full Control rights on
the SharePoint site.

The SharePoint site is located in the local intranet group; User
authentication is set to "automatic logon with current username & password"

The mapped drive is always disconnected at logon, accessing it results in a
logon&pwd popup labeled with a "Incorrect password or unknown username for
[\\intranet\target folder]" error message.