Installation problems, cannot boot from cd drive

[Dalston]

Hello im trying to reinstall XP and then ubuntu 8.04, both from disk. The problem is when I restart and then press f12 to change it to boot from cd, nothing happens it just boots up ubuntu. I have tried using 2 different versions of xp that I have previously used to install and my original version of ubuntu, all 3 end the same way. Can someone help me out please.
Thanks

[father time]

Message Deleted.

[Dalston]

Does someone know of a reason why it wont let me boot from start up?

[Dalston]

I've been a member of these forums for a few years and it never fails to solve my problems.

ok sorry forgot to put all the relevent info.

1. Yes I have previously installed from both copies of xp and also the 7.04 live cd.
2. I have an AMD Athlon 64 processor 3200+, 512MiB ram
3. I am using ubuntu 8.04 upgraded from 7.10 upgraded from 7.04.

[father time]

Message Deleted.

[Dalston]

Thanks for your help, I think its a Grub issue because after I press f12 it doesnt give me the option to 'press any key to boot from disk' it just goes straight to starting up Ubuntu. Im not using the amd64 distro im using ubuntu-8.04-desktop-i386

[lowstand]

most computers you hit F2 to get to bos an then just go in an ask it to boot from cd or if you have the built in restore on your drive it will give you the option under your boot from most of the time

hope this helps

[oilchangeguy]

Thanks for your help, I think its a Grub issue because after I press f12 it doesnt give me the option to 'press any key to boot from disk' it just goes straight to starting up Ubuntu. Im not using the amd64 distro im using ubuntu-8.04-desktop-i386

grub has nothing to do with the boot selection. when your computer is posting (Power On Self Test) the operating system is not yet involved. try entering the bios and setting the boot from there.

[JMorg]

Definitely try Oilchangeguy's option of manually/permanently altering it within the BIOS. Make your optical drive the primary boot device, and if that doesn't fix your issue then attempt to use a new optical drive or an external optical drive because i'm venturing to say that your hardware is failing.

[Dalston]

Ok update: I still cant boot an xp disk from boot, I have tried altering the bios but I cant boot, sometimes I get the error 'cannot boot from cd error 5' and sometimes I get 'cannot find NTLDR' anyone got any ideas?

edit: Oh yeah I tried both disks on another pc and they both booted fine.

[Dalston]

Sorry for the bump but I am at a loss as of what to do.