Visual Basic - Error en tasks.exist al cambiar de office 2000 al 2003

Function HayDocumento() As String

Dim documento As String, buf As Variant

Dim winName As String, hndl As Long

   On Error GoTo HayDocumentoErr

   'lo de abajo genera un error si no esta abierto Word

   buf = Tasks.Exists("Microsoft Word")

   If FindWindow(0&, "Microsoft Word") = 0 Then 'si tiene docuento

      winName = Tasks.Application.ActiveDocument.Name

      winName = Left(winName, Len(winName) - 4)

      If IsNumeric(winName) Then

         doc = winName

      End If

   End If

HayDocumentoExit:

   HayDocumento = doc

   On Error GoTo 0

   Exit Function

HayDocumentoErr:

   Resume HayDocumentoExit

End Function