Of all the DVD players I've worked with in the past, Sony DVD are the most picky of them all. You have to be sure of a few things, do the video files on the disc meet DVD standards. Is the media of good quality and does your burner support that media. I've come across that problem in the past with my old Lite-On DVD burner with 16X media and it wasn't supported. I've burnt 5 until I came to the point of nearly tossing that burner through the roof. Luckily I managed to get a deal on a Plextor 716A and the 16X Ritek DVD+Rs worked without a problem. Also another problem that I've come across with my Sony DVD player was on T2 Extreme Edition. I would get the disc is dirty error message, the reason for this was because DVD Rebuilder was handling ILVU or multi-angles improperly. This resulted in error messages time and time again. You can't test these discs on a PC DVD player because anything should play fine regardless, but on a Sony DVD player if it works then it'll work on all players. What I did was, got my hands on a simplistic DVD editing program called DvdReMake Pro and removed the extra angles on the disc. All Star Wars DVDs have multi-angles so you can play around with that in the meantime.
You can play around with programs such as VobBlanker, IfoEdit and PgcEdit which is a program I use to certain that the disc meets DVD standards before burning. Also be sure to run a verification test after the burn with ImgBurn because all sorts of errors can arise from bad media, to fast write speeds or damaged memory sticks.
Latest firmware for your burner is listed below...2004.
http://www.cdfreaks.com/drive/firmware/1140
Jam it back in, in the dark.