Another question re:DVD player problem

The Marantz DV 4300 I mentioned in my query below is almost two years old. Lately, I have come across DVDs which played through OK to about the half way mark (layer change area I suspect) and then frozen completely. The only way I could finish watching the film was by playing it on my son's playstation. It only occurs with some disks - the majority no problems. For example, I just re-watched the entire three extended editions of LOTR without a single glitch.

Can anybody shine any light on this puzzling problem?

PS: I cannot blame worn or dirty disks because the latest problem occurred with a new disk straight out of its sealed box. I have noticed that the disks get quite warm in the machine - is this normal?

The only thing that I can think of, is discs have built in error code. Your player is reading an error from these movies for whatever reason possibly the laser can't read the info and is not able to resolve it, gets stuck. Just a guess.