I think i know what the problem is:
The error occures when the 12th step is being copied. I just downloaded a previous version that is broken down into 3 CD's not 1 DVD. At the 12th step it asked me to insert the second disk. Therefore it seems like error comes up because the map loader cannot locate the right files to copy from the source. Not sure how to fix it, but this might give some of you a starting point. I am just going to work with the previous version.
t.