Hola!!
Si lo que quieres es que el boton "X" este deshabilitado pero que se vea lo que tines que hacer es esto:
Private Declare Function DeleteMenu Lib "user32" (ByVal hMenu As Long, ByVal nPosition As Long, ByVal wFlags As Long) As Long
Private Declare Function GetSystemMenu Lib "user32" (ByVal hWnd As Long, ByVal bRevert As Long) As Long
Private Const MF_BYPOSITION = &H400&
Private Sub Form_Load()
'// remove the close menu (which then disables the close button)
RemoveMenus
End Sub
Private Sub RemoveMenus()
Dim hMenu As Long
' Get the form's system menu handle.
hMenu = GetSystemMenu(hWnd, False)
DeleteMenu hMenu, 6, MF_BYPOSITION
End Sub
De esta manera tendras los botones maximizai, minimizar y cerrar visibes pero el de cerrar estara deshabilitado.
Hasta otra!!