Public Class Form1
    Inherits System.Windows.Forms.Form
 
    Dim TabPage2_enable As Boolean = False
 
    Private Sub TabControl1_SelectedIndexChanged(ByVal sender As Object, ByVal _
      e As System.EventArgs) Handles TabControl1.SelectedIndexChanged
 
        If TabPage2_enable = False Then
            TabControl1.SelectedIndex = 0
        End If
 
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
 
        TabPage2_enable = True
 
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
 
        TabPage2_enable = False
 
    End Sub
 
End Class