You will always be the teacher, and I the student.
I was not aware that copy protction with intentional errors produced that error message, thank you for educating.
Sometimes I assume things without having all the facts. I always keep my CloneDVD and AnyDVD updated so when I get an Cyclic Redundancy Check data error it has always been a defective disk for me. I have tried all the software available without any luck in copying the disk, solution always was disk replacement that solved the problem.
I always clean my disks before the read stage, but here again I'm ASSUMING others do the same, it very well may be a dirty disk as you and bkjg suggested.
In addition I should not have assumed he/she was using AnyDVD, person never said what they used to remove the copy protection.
I usually burn brand new store bought DVD's and these error messages seem to be appearing more frequently these days. I usually clean out of the box with a damp cotton cloth and dry with a clean cloth. On some older DVD's that I've gotten the message on, I tried tooth paste, rinse and dry, then apply some Pledge furniture polish as some people have suggested to remove scratches, never worked for me.
Only time I ever used Brasso was to clean my belt buckles while in the military,
what the heck, next time I'll give it a try and see if it works as it has for you.
Thanks for the tip.
What software did you use to remove the copy protection?
Kindly advise if by thoroughly cleaning the disk if this removed the error message.