I've followed the instructions in the pinned thread to the letter, but the game still fails to set up the vitual disk file system. What else could be going on?

Is the installer version 2.6 or 2.7?

I just purchased it and I'm pissed off that it's 2.7, which I think can't be modded!

I had installed this game sometime last November. I believe I had no problem installing systempack 1.8. You'd like to refer to their installation steps on worldofgothic. There might be a file that downgrades to 2.6.