Desabilitando teclas ctrl+alt+del, alt+tab, ctrl+esc

//(Ctrl+Alt+Del),(Alt+Tab), (Ctrl+Esc)
var
OldValue : LongBool;
begin
{liga a trava}
SystemParametersInfo(97, Word(True), @OldValue, 0);
{desliga a trava}
SystemParametersInfo(97, Word(False), @OldValue, 0);
end;