Hi sirquack,

Sadly, it seems like development of DVD Decrypter ended in June 2005. If the version you have is the most updated and does not work, see the link below for more info on DVD Decrypter's sad ending and links to alternative backup software:

http://www.afterdawn.com/software/video_software/dvd_rippers/dvd_decrypter.cfm

(DVDFab Decrypter is freeware and is updated).

Hope it helps.