I'd completely rewrite the whole thing along these liens:
Code:

$=SetConsole("minimize") 

Break On 
;Dim $Form 
$Form = CreateObject("Kixtart.FORM") 
$Form.CAPTION = "Authentication for @FULLNAME" 
$Form.SCALEWIDTH = 300 
$Form.SCALEHEIGHT = 60 
$Form.FONTSIZE = 8 
$Form.FONTNAME = "Verdana" 
$Form.PrintXY(15,6,"Enter authenticity Key and press Button") 
$Form.CENTER 

$txtpassword = $form.textbox("",15,30,100,20) 
$txtpassword.passwordchar = "*" 
$txtpassword.text = "" 
$PSWB = $form.Button("Validate",125,30,100,20) 
$PSWB.OnClick = "PasswdC()" 

$Form.Show 
While $Form.Visible 
  $=Execute($Form.DoEvents()) 
Loop 
$Form=0
IF not $authenticated
  exit 2
endif

; do the main form
; (Here will the secound script begins, if Authentication is OK ) 
Break On 

$Form = CreateObject('Kixtart.Form') 
$Form.BackColor = 212,208,200 
$Form.ControlBox = "True" 
$Form.DrawGrid = "True" 
$Form.FontBold = "False" 
$Form.FontItalic = "False" 
$Form.FontName = "Tahoma" 
$Form.FontSize = 8 
$Form.FontUnderline = "False" 
$Form.ForeColor = 0,0,0 
$Form.FormBorderStyle = 3 
$Form.Height = 580 
$Form.Left = 11 
$Form.MaximizeBox = "False" 
$Form.MinimizeBox = "True" 
$Form.SizeGripStyle = 2 
$Form.StartPosition = 4 
$Form.Tag = "" 
$Form.Text = "My Script" 
$Form.Top = 3 
$Form.ToolTipText = "" 
$Form.TopMost = "False" 
$Form.Width = 800 
$Form.WindowState = 0 

sleep 10

Function PasswdC() 

If $txtpassword.text = 'validate'
  $Authenticated = 1
EndFunction



there are other ways to do thsi, e.g. initializing the KiXforms system first, then create the password prompt. If success create the main form else display a messagebox and exit.
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