VBS script used to overwrite, now makes (unwanted) copy

I have a simple VBS login script for all my users that checks a location on our server and updates (by overwriting) the same files on the users' PCs if the server copy is newer (FSO.CopyFile etc). This has run swimmingly for several months now, but today I discovered it ISN'T overwriting the local files, but rather creates a copy of any replaced file, in the standard Win 7 format of Filename - Copy.ext.

Is this some Windows component with its Mom Switch set on high, trying to be helpful/protective? The problem it creates is this: some of the files the script updates are VBA add-ins containing a suite of Word macros; and if 2 files in the macro-supplying folder contain same-named macros, *neither* macro of the conflicting pair is available to the user.

This is a recent change -- that is, it’s not something that's been happening all along but only recently noticed.

Even stranger -- or perhaps this is a clue -- this *doesn't* happen on my home PC, which is identically equpped except for different AV programs (work=Comodo, home=Avast).

All PCs are Win 7 Pro 32-bit with Office 2010.

Any ideas? I know I could change the script to delete the to-be-updated files before overwriting, but that seems like surrendering to the vampire.

It's below. I hope it's decipherable but I fear it may not be. (I'm not so diligent about commenting code.) FYI the notation 'AAI' is just our shorthand for the name of the macro suite. The 'guts' of the code begins after the 'copy or update files' comment.

Code:

   Dim oFSO 
   Dim oShell
   Dim oAppDataFolder

   Set oFSO=CreateObject("Scripting.FileSystemObject")
   Set oServerUT = oFSO.GetFolder("Z:\Users\AAI\UT\")
   Set oServerSU = oFSO.GetFolder("Z:\Users\AAI\SU\")
   Set oShell = CreateObject("Shell.Application")
   Set oAppDataFolder = oShell.Namespace(&H1a&)

   WSF = oAppDataFolder.Self.Path & "\Microsoft\Word\Startup\"

   Set oShell2 = CreateObject("WScript.Shell")
   Hpath = oShell2.ExpandEnvironmentStrings("%HomePath%")
   
   '===set local AAI file path
   sAAI = "C:" & Hpath & "\AAI\"
   sAAIUT = sAAI & "UT"
   Set oAAI = oFSO.GetFolder(sAAI)
   Set oUserUT = oFSO.GetFolder(sAAIUT)

   '====copy or update files
   Set colFilesUT = oServerUT.Files
   For Each oFile In colFilesUT
      If Instr(oFile.Name,"~")=0 Then
         sLocal = Right(oFile, Len(oFile.Name) - InStrRev(oFile.Name, "\"))
         If Not oFSO.FileExists(oUserUT.Path & "\" & sLocal) Then
            'not found on local PC, so copy
            oFSO.CopyFile oFile.Path, oUserUT.Path & "\"
            bUpdated = True
         Else
            Set oLocalFile = oFSO.GetFile(oUserUT.Path & "\" & oFile.Name)
            If oFile.DateLastModified > oLocalFile.DateLastModified Then
              'found older on local PC, so replace
               oFSO.CopyFile oFile.Path, oUserUT.Path & "\"
               bUpdated = True
            End If 
         End If
      End If
   Next

   Set colFilesSU = oServerSU.Files
   For Each oFile In colFilesSU
      If Instr(oFile.Name,"~")=0 Then
         sLocal = Right(oFile, Len(oFile.Name) - InStrRev(oFile.Name, "\"))
         If Not oFSO.FileExists(WSF & sLocal) Then
            'not found on local PC, so copy
            oFSO.CopyFile oFile.Path, WSF
            bUpdated = True
         Else
            Set oLocalFile = oFSO.GetFile(WSF & oFile.Name)
            If oFile.DateLastModified > oLocalFile.DateLastModified Then 
               'found older on local PC, so replace
               oFSO.CopyFile oFile.Path, WSF
               bUpdated = True
            End If 
         End If
      End If 
   Next

   On Error Resume Next 
   Set oShell = Nothing
   Set oShell2 = Nothing 
   Set oFSO = Nothing
   Set oAppDataFolder = Nothing
   Set oServerUT = Nothing
   Set oUserUT = Nothing
   Set SystemSet = Nothing
   Set oAAI = Nothing
   Set oHT = Nothing
   Set colFilesUT = Nothing 
   Set colFilesSU = Nothing 
   Set oLocalFile = Nothing
   If bNewInstall = True Then 
      MsgBox "Install successful."
   End If

Thanks. That's interesting. But is there a reason this third parameter would be required on some systems and not others? (The differently-behaving machines are very similar, even similar Dell models purchased the same month!)

I appreciate the tip.