Hi :)
Kubuntu Cd should boot up just fine. Is there a problem with the Cd or the Cd/Dvd-drive? Can you get another machine to create a new Cd? Can you check the Md5sum on the old Kubuntu Cd? Cds do get scratched and damaged sometimes and i have found Cds become unbootable at the slightest thing. So, i tend to make a few at a time. A good fresh one might solve the problem.
Hopefully someone else on this list might give a better answer.
Good luck and regards from
Tom :)