There's no need to use a timer, you can put your trap in the form's sizechanged event :

Code:
    Private Sub Form1_SizeChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.SizeChanged

        If Me.WindowState = FormWindowState.Minimized Then
            Me.WindowState = FormWindowState.Normal
        End If

    End Sub
Its not an ideal solution though as you will get a flicker as the form is minimized and then restored.