at first i would think that you are having problems with copy protections. dvdshrink and dvd decrypter are no longer being updated and dvd43 was last updated April 9, 2008. now i dont know much about dvd43 so im not certain how well it really works.
you could also be experiencing scratched or dirty discs. if the disc is readable in a standalone player does not necessarily mean it will read properly in a dvd drive. if the problem is scratched or dirty disc, besides cleaning there is not much which can be done. there are other solutions which i dont recommend. you may find them by searching google.
you may also have bad dvd media and burning too fast. please post burn logs for review.
if the problem is copy protections, i have three suggestions.
use anydvd as background decrypter similar to dvd43. you can use anydvd with dvdshrink, nero and dvd decrypter. there is a trial so you can try before you buy.
use free dvdfabhd decrypter. you can rip the video to the hard drive then reauthor with dvd shrink and burn with nero or dvd decrypter.
use dvdfab platinum. this is an all-in-one program. decrypt, rip, reauthor, compress and burn in just a few easy steps.