laptop with xp keeps rebooting

hi! I have this asus laptop. it worked just fine up until a few days ago when I started it, but it just kept on rebooting. I have to say that I tried the safe mode but it does the same thing. I reinstalled windows, but nothing. Since I can’t get into the system.. I don’t know what to do..the last good configuration gave an error that kindly invited me to disable some stuff, but since I can’t go in to the safe mode, I can’t disable a thing. so… now what?