Reinstall problem

Hello,

My PC keeps freezing after 5 seconds everytime I turn it on ,so I have inserted the XP CD-Rom to try and reinstall it and that freezes after 5 seconds too , it gets as far as ' press and key to boot from CD' and then freezes , does anyone know what is causing this or how I can get the pc to complete the reinstallation process? I can even look at the BIOS settings because it freezes as soon as I select DEL and go to the setup utility screen!!!! someone please HELP!!!