I sent a set of DVDs copied on the 4120B to someone with a Toshiba player and the last 2 episodes of all 23 discs wouldn't play right. I sent her the same discs done on the NEC and they play fine. I sent a set of something else done on the LG to someone else and they wouldn't play on his JVC. I had one other person tell me that discs done on the LG would pause for a second on 2 of her 3 players. I haven't found anything that won't play the NEC discs yet. Just wanted to give a little info for anyone looking at either burner. All of them were Prodiscs.