Actually we are all lame the problem is you are using the DIRECTORY.Move method instead of the FILE.Move method.
VB Code:
  1. Dim sysPath As String = Environment.GetEnvironmentVariable("windir")
  2.         Dim filename As String = "text.txt"
  3.         IO.File.Move(IO.Path.Combine(Application.StartupPath, filename), IO.Path.Combine(sysPath, filename))

Although rename takes the same basic parameters as move so the only difference would have been to use Rename instead of Move.