it simply means that your cd/dvd cant read the data on your disc... try to check if your disc has scratches on it-if it is clean try to check if your cd/dvd drive is working good... if it fails, check the ide/sata cables if it is properly connected... are you using burned cd/dvd from ISO image?if yes, make sure to burn it at a fairly slow speed to avoid data corruption... good luck! PM me for updates if it still show errors..