Cant boot from the CD after installing Ubuntu

[J]

On Wed, Oct 3, 2012 at 5:36 PM, Wade Smart <wadesmart at gmail.com> wrote:
> On Wed, Oct 3, 2012 at 3:10 PM, Avi Greenbury <lists at avi.co> wrote:
>> Wade Smart wrote:
>>> I have a laptop with XP on it and I finally decided to try 12.04 LTS.
>>> I installed it side by side. Now I cant boot from the CD even when
>>> going into the boot menu.
>>
>> The boot-from-CD function is something that happens far too early for
>> Ubuntu to have much of an effect on this. What actually happens when
>> you try to boot from CD? Do you get any error messages? Can you boot
>> the same CDs on other machines?
>>
> After pushing the on button and I see "Hit F10" for
> boot order and when I do and select cdrom for the
> first choice, you hear the cd drive spin up and then
> the screen blinks once or twice and you now see the
> initial purpleish screen to choose Ubuntu, ubuntu recovery,
> memory test, a different memory test or Windows XP.
>
> You cant at any point boot from the cd.

As Avi said, booting from CD takes place in the system's Firmware,
well outside of the Grub or XP Bootloaders, they have nothing to do
with this.

After the system finished POST, it then starts looking through the
boot order (set up in BIOS, or as you mention, by selecting an option
after hitting an F key to invoke the menu directly).  So in your case,
what happens is your machine POSTs you hit F10 at the prompt and get a
boot menu.  You select the CD drive.  The system then spins up the
drive, which you hear.  You may also hear the laser being moved back
and forth across the disk as the drive searches for a bootable data
sector.

The screen blinking once or twice could be one of two things... A: the
optical drive does find a bootable sector, tries booting from that and
fails, or B: the optical drive fails to find the bootable sector, and
the blinking is just a product of the system resetting a bit before
moving automatically to the default boot item, which is the HDD in
your case.

So one of two things is happening here, most likely.

1: Your optical drive is bad
2: the CD is bad, scratched or dirty

Beyond that, you may have more deeply involved issues (bad RAM could
also be a culprit) but this all happens outside of the OS and
Bootloader on the hard drive, so they really have nothing to do with
it.

If you have a laptop with XP on it, I'm going to bet it's fairly old,
so a failing or failed CD drive is certainly a likely culprit here.