160P6S freezing when some original DVDs inserted

hi, ive just bought a 160p6s as a replacement for another liteon drive that had been playing up for a while. but it won’t play a couple of dvds. theyre originals, and the right region code and everything but the green light just stays on constantly, and if i try to play the disk or view the files the player or window just goes non-responsive until i eject the disk.

the 2 things i find strange, is that the drive ive just got rid of, wasnt reading a box set of dvds id just bought (it kept saying ‘please insert disk’) even though they played on everything else. yet these disks work on this new drive.

the other strange thing is that i have 2 fitness dvds - same make, company even got em from the same place. ones the follow up from the other. yet the first is one that makes the drive freeze but the 2nd one plays perfectly.

has anyone else had the same problem? any idea of how i could fix it? (btw i dont actually know how many dvds wont play since ive oly just got the drive)