From what you describe, it sounds like a media issue to me, especially as the Sony burner cant read its own creations.
Before changing software etc., try using a Ritek disk. These are well renowned for their reliability & compatibility, with both burning and playback in standalones.
If you can burn your movie ok to a DVD+RW, then you should not have trouble doing likewise to a DVD+R.
One thought that comes to mind is, your film is 2hrs 40 mins, which is likely to occupy pretty much all of the disk, hence it will be burnt right up to the outer edges of the disk.
Some burners and players have trouble writing/reading to the extremities of the disk and some brands of media give up the ghost here too.
It may be worth trying a burn a disk, with a smaller filesize to check this aspect. If this produces a good burn, then it's easy to compress your larger files a little, using Dvd2one or similar. Also if this sems to be the issue, a Ritek disk may work where others fail.
Hope this helps.
P.S. Also Have you tried a DVD-R