I'm having problems figuring out why these 2 players will have problems with certain dvds (original copies).

first, the sd1700 will not bootup either star Wars Episode 1 or even 2 sometimes without having to switch the machine on or off several times, remove re-insert the disc, still the same message: error reading disc or else it wont even boot to the disc's main menu (sometimes this happes, sometimes it doesn't). My workaround was to take out either star Wars disc, place another movie in. Wait till the machine boots to the disc menu. hit eject, then place the star wars disc in and away it goes. Can anyone offer an explanation.

Now, my sd4700 which usually plays everything, is unable to read an orginal copy of the bollywood movie Devdas. This is suppose to be an original copy of the movie (ebay purchased), but it looks like a 'no name studio' (Eros International?) and doesn't seem to be made too well. When placed in the sd4700, I only get the message: Disc Error. BUT surpisingly, the sd1700 WILL play this disc without any hesitation! I thought it would've been the other way around. Any ideas on that one?

What makes a movie playable on one dvd while being unreadable on another?? when is a dvd not a dvd?

Any insight on this confusing issue would be appreciated.