ciao a tutti, recentemente ho tirato su un programma per bloccare il computer con una password in modo da protegerlo da "guardi indiscreti" di cui vi fornisco il codice sorgente:

codice:
Public Class Form2     
Dim canClose As Boolean = False       

Private Sub Form2_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing         
If Not canClose Then             
e.Cancel = True         
End If     
End Sub          

Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged         
If CheckBox1.Checked = True Then             
TextBox1.UseSystemPasswordChar = False         
End If         
If CheckBox1.Checked = False Then             
TextBox1.UseSystemPasswordChar = True          
End If      
End Sub      

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click         
MessageBox.Show("Computer bloccato con password", "Locker", MessageBoxButtons.OK, MessageBoxIcon.Information)         
Label1.Visible = False         
TextBox1.Visible = False         
CheckBox1.Visible = False         
Button1.Visible = False         
Button3.Visible = False         
Label2.Visible = True         
Label3.Visible = True         
TextBox2.Visible = True         
Button2.Visible = True         
Label4.Visible = True      
End Sub      

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click         
If TextBox2.Text = TextBox1.Text Then 
canClose = True             
Me.Close()             
Form1.Close()         
Else             
MessageBox.Show("Password errata!", "Locker", MessageBoxButtons.OK, MessageBoxIcon.Error)         
End If     
End Sub      
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click         
canClose = True         
Me.Close()         
Form1.Show()     
End Sub      

Private Sub Label4_DoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Label4.DoubleClick         
canClose = True         
Me.Close()         
Form1.Close()     
End Sub End Class
il programma funzia pefettamente, ma se durante il blocco premo ctrl alt canc mi apre il task manager e posso terminare il processo del programma....

come posso ovviare al problema?