Hi everyone,
I recently did an iso file of the game (v1.29f) and tried to mount it on D-Tools. Even if I used the proper security options and tool to create this ISO (Alcohol) it failed.
After a few tests I realized that some weird security check is made to validate if the CD is in the drive you originaly installed the game from.
So by changing the associated letter on the mounted virtual drive accordingly, I managed to make the game work.

It's the first time I hit this type of security check. However, I must admit I haven't used mounted images for gaming purposes very often. Is it a common practice?