BIOS boot sequence

Hi,
I have this problem with my XP, some registry file is damaged or something and I wanted to use the XP CD to repair the OS. I wen't to the BIOS Setup and changed the boot sequence so the computer boots from the CDROM. My problem is, it isn't booting from the CDROM, it skips to the HD, at least I think it does, because the XP setup doesn't show up. I don't know what I am doing wrong here, so I am asking you to help me with this. My BIOS is a Phoenix, if that helps.

Thanks in advance.

Do you have an original XP install disc?
Have you successfully booted from the disc previously?
Have you tried the disc on another computer?

Did you save changes when you exited setup?
Can you hear the disk spinning in the drive?
If you have 2 CD drives make sure you put the disk in the master drive.
Also the disk could be scratched . Have tried cleaning it?

Silly me, I was using the slave drive. Thanks for the help!