Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Interval = TextBox2.Text
        Timer1.Enabled = True
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Timer1.Interval = TextBox2.Text
        Timer1.Enabled = False
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        SendKeys.Send(TextBox1.Text)
        SendKeys.Send("{enter}")
    End Sub
End Class