use stopwatch instead. you can change the Elapsed to whatever you want (minutes, milliseconds, etc)
Dim sw As New Stopwatch
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
sw.Start()
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
sw.Stop()
MessageBox.Show(sw.Elapsed.Seconds.ToString)
End Sub