Liteon 401s

my pc is causing concern it will not read backups of any dvd’s i am using liteon 401s + dvd rom drives with xp home whenever i try to do another backup using dvd shrink or decrypter it tries to read the disc but cant or wont 1700 cpu + 700mb ram so have plenty resources.

any help please at the moment i have to use other peoples drives and pc’s