System Delphi

Title: Check if time has been changed
You should intercept WM_TIMECHANGE message.
Implementation of this idea is so:
type
TForm1 = class(TForm)
Label1: TLabel;
private
procedure MyMessage(var Msg: TWMTimeChange); message WM_TIMECHANGE;
{ Private declarations }
public
{ Public declarations }
end;
...
procedure TForm1.MyMessage(var Msg: TWMTimeChange);
begin
if Msg.Result=0 then
Form1.Label1.Caption:='OK';
end;