Burningproblems!

Hello!
I)´m a newbie to burning so I´m hoping this is the right forum to post this topic.
I´ve recently bought a computer with a DVD-and CD-writercombo.
I have burned several CD´s with excellent result and now i´m trying to burn DVD´s. I want to copy a regular DVD-film to a DVD+R.
I use DVD dycrypter, DVDShrink and Nero Burning-ROM, both the latest version. My DVD-burner is a brand new Samsung 12X.
All goes fine until i start watching the film. On my stationary DVD-player (NAD T531) the movie starts to break up into digital pieces (both sound and picture) after about half through the film. The longer it goes, the worse it get´s. Eventually it all stopps and I must restart the NAD.
The same thing happens when I try to watch the (DVD+R)-film on the computer. The only difference is that the breakdown happens later in the film (a couple of chapter later).
When I start the film everything is fine (both on my computer and on my NAD), good quality in picture and sound.
I´ve tried several different brands of media. Non works! I´ve tried to burn on the following media: Traxdata DVD+R 4X, Traxdata DVD+R 8X, Bulkpaq DVD+R 4x, Bulkpaq DVD-R 4 x.
I have tried to burn in different speeds (1X-8X) and it doesn´t get any better.
The "original" disc is in excellent shape.
I´ve uppgraded the firmware for the burner. The result was much better. Only the last 4 chapters on the DVD were in bad shape when I burned on Bulkpaq DVD-R 4X,DVD+R 4x and Traxdata DVD+R 8X.
On one film the subtitle wasn´t in sync with the audio in the last part of the film.

Today I have done everything I can think of. Firmware and software are up to date. Virusscan and programs (like Internet explorer) are closed before ripping and burning. A good media is used and the original disc is in excellent shape.
I read that Pinnacle Instant CD/DVD could cause problems with other softwares (like Nero) so I removed it completely before I started ripping and burning.
I only execute one step at the time, first ripping to the harddrive with DVD Decrypter, then shrinking with DVDShrink also to the harddrive and at last burning with Nero Burning ROM.
After ripping I watched the film from the harddrive, no problems.
Then I shrinked it and watched the film again from the harddrive, no problems.
Then I burned it and Nero verified the burning as successfull.
Now I tested the DVD with Nero CD/DVD speed, no problems, all of the disk were good and no readingproblems.
But here comes trouble. Then I watched the film on my computer, now it started breaking up towards the end, just like before.
When I watch the film on my stationary DVD-player everything is fine!!! For a couple of days ago (before i removed Pinnacle and killed the virusscan and IE) it was the opposit.
Shouldn´t it still be worse on my stationary player than on my computer??? And the really big question, How can I make the film to work on the computer??? The original DVD plays without problems on the computer.
This is really killing my.
What more can I do??? Please help me!