DVD play freezes on Bourne Ultimatum

Try to watch Bourne Ultimatum on pc. Iam using Liteon dvd 20A1P KL0N . I can only watch half of the movie , then it freezes at the part where Jason Bourne calls Pamela Landy and says " I hear you are still looking for me ". Any idea what could be the problem. This is the first for this to happen. When I try to backup the dvd , decrypter says there are errors trying to read Vob 4 and cancels process. Any info would be greatly appreciated. Thanx in advance cat53

It seems this is a widespread problem with this particular dvd. I had the same problem as you tonight and returned my copy twice in an attempt to remedy the situation. Not only did it freeze on my computer but in a stand alone unit as well (with all 3 copies). It locks up at the same exact part you described. I was enjoying the movie too!