GRUB error 21 - LiveCD doesn't boot

[Timothy Ha]

My laptop won't boot Ubuntu's LiveCD because of GRUB error 21.
I can install Warty, though. Warty CD boots in the same laptop.

P.S: Big thanks for the CD offer. I received a good package of Intel 
x86, AMD64 and PowerPC editions. Intel CDs installed on a big PC, then a 
laptop. PowerPC edition got its place on a Powerbook G4, it recognized 
the Apple hardware, so multimedia features worked.