Private Sub Button1_click(ByVal sender As Object,ByVal e A System.EventArgs) _
  Handles Button1.Click
    Dim oThread As New System.Threading.Thread(AddressOf ChangeProgressBar)
    ThisForm = Me
    oThread.Start()
End Sub
 
Private Sub ChangeProgressBar()
    For i As Long = 0 To ThisForm.progressBar1.Maximum
      ThisForm.progressBar1.Value = i
    Next
End Sub

Private PbMax As Long = 1000
Private PbVal As Long = 0
 
Private Sub ChangeProgressBar()
    For i As Long = 0 To PbMax
      PbVal = i
    Next
End Sub