How to clean Scratched CDs DVDs with Toothpaste

Last week i am installing windows XP from my XP cd. But in the half way, I got error "Cannot copy ps.dll. Make sure the Cd is in the drive." I try again and again but i am not able to install my xp. I took my XP cd out if CD drive and there are some scratches on it. Have you ever come acrooss a situation like this.Well, If you've ever owned a CD or DVD, you've certainly had to deal with scratched