I was having trouble making a backup DVD for Final Fantasy X here. All of the programs I tried had no trouble reading the disk though. But the PS2 would not read the copies made by Alcohol 120% or by Nero. I used a Plextor burner for them. I then swithced over to my laptop because it has the latest Blindwrite Suite on it and a Pioneer burner. All of the backups from it have worked ..... I did the first on a RW DVD to make sure it worked and then burnt a -R disk. Not problems with either.
I should also note that all other backups done with the Plextor burner and Alcohol 120% have all worked! It was only the large game Final Fantasy X (4.2 gigs) that I had a problem with.
So there appears to be no protection that would stop your programs from reading at 50%. It must be an problem with the disk that you are trying to read. Especially if all the programs stop at the same area of the disk!