Private Sub Timer1_Tick(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles timer1.Tick
 
        Static bmp As Bitmap
 
        picturebox1.Image = Nothing
        If bmp IsNot Nothing Then
            bmp.Dispose() : bmp = Nothing
        End If
        bmp = screencapture()
        picturebox1.Image = bmp
 End Sub