Thanks for the advice!
I just managed to get one "The Shadow of Death" working, which I have a licensed copy of, but the disc is lost. And it won't run without the disc.
All the others still refuse to work, darn it! :(
I've already tried giving them different files – it's useless.
Here's what I did:
I created an image from the licensed disc using Nero 6, and I've even forgotten where the disc itself is now...;)
I load the COD image and enjoy it:)
Advice: Borrow a disc from a friend, create an image, and play without worries!;
Best regards, VDV_forever