prova così , sul mio server funziona correttamente:
codice:
<%

download = "Nometuofile.est" 'in alternativa utilizza download = rs("download")

Set fsoMyFile = CreateObject("Scripting.FileSystemObject")
fsoMyFile.CopyFile Server.MapPath("download/"&download&""), _
                                  Server.MapPath("temp/"&download&""), True

Set objStream = Server.CreateObject("ADODB.Stream")
objStream.Type = 1 'adTypeBinary
objStream.Open
  
strFileName = "temp/"&download&""
objStream.LoadFromFile Server.MapPath(strFileName) 
  
Response.AddHeader "Content-Disposition", "attachment; filename=" & strFileName 
Response.ContentType = "application/octet-stream" 
Response.BinaryWrite objStream.Read
  
fsoMyFile.DeleteFile Server.MapPath("temp/"&download&"")
  
objStream.Close
Set objStream = Nothing
                                
%>