It's works !
The netbook asked for this code on 2 or 3 reboots and disabling it was impossible.
Now it boots without it, I think i't's because I didn't use it for a long time and the motherboard batery was empty.
Many thanks !
PS : I'm french, so my keyboard is AZERTY, for thosse who the code doesn't work, try to enter it with a QWERTY keybord in mind ;)