DVD Decrypter was stopped in development a long time ago, it doesn't support many DVD's anymore. The programme to use it DVDfab HD Decrypter available at
http://www.dvdidle.com/free.htm
The HD decrypter is a later version on their DVDfab Decrypter, and it supports HD and blu-ray. The programme has significantly improved with version 3 and the improvements in version 3 have also been excellent.
The error shown looks like an error on the DVD. Have you made sure there are no marks/smudges/transparent residue on the DVD? Its important that optical media are kept clean and especially smudge free, smudges are actually worse than shallow fine scratches! Check the DVD and make sure there aren't any surface aberrations (that is, like the recorded surface doesn't look even.