Hello to everyone and thanks to anyone who answers this for his/her time.
Well, I have the computer that I mention on the title and I found that after booting the live CD up (with EFI), when the system starts loading it just hangs up always at the same point, more or less: when it is stopping the anac(h)ronic cron service. The CD reader just stops working and the loading process stops there. I use as boot option the nomodeset (because if I don't do so the screen just starts flickering) and I removed the splash and silent options to be able to see where it doesn't work.
If that's any help, I have windows 8 installed on the computer and I planned to do a dual boot with ubuntu 13.04.
Thanks again to anyone who answers this question!