To minimize or hide the form with using the buttons,
use
Base Class Events - Closing

Code:
Private Sub frmMain_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
        Me.Hide()
        Me.WindowState = FormWindowState.Minimized
        e.Cancel = True
    End Sub
Instread of
Code:
Me.Close
(unloads the form) use Me.Hide[/CODE] to hide to screen or
Code:
Me.WindowState = FormWindowState.Minimized
to minimize the window.

Use the
Code:
e.Cancel = True
to tell the form that its not allowed to shut down

To exit the application use the
Code:
Application.Exit
command