Welcome to the forum Nando
More than likely your problem may lay with the discs you are using, but lets look at your method first.
I think you could cut some step and perhaps save time by using some different programs to achieve the same final goal.
- Rip with DVDFab HD Decrypter
- Compress with DVD Shrink (you already say you have that)
- Burn with Imgburn
Here is a link to a version of DVD Shrink that will allow you to autoburn with Imgburn ~ http://www.dvdplusvideo.com/DVD_Shrink_3_2_b_w_IB.zip
Here is a guide for using all those programs together ~ http://www.dvdplusvideo.com/Guides/alkohol_guide1.html
Let us know if you have any more questions.
Now for the discs…what brand are you using? Most people find that Verbatim have a higher degree of success and compatibility with burners and standalone players.