Distro specific boot problems

I got installation disk for various distro's (Ubuntu, openSuse, Slackware, etc) and all of them boot just fine on my laptop (Asus M51S). So I can safely assume the problem is not with the disks.

However, from a desktop computer I have (Dell .... at work now, cant remember the model), trying to boot from most of these disks (Ubuntu Hardy Heron and Slackware boot just fine) does not work.
The computer just boot up to the bootloader as if no cd are present.

So I know the installation disks are fine (seeing all boot on the asus), and i know the dell is fine (as it boot from *some* disk, including wix xp).

Anyone ran into issue like this before?