Hi FlorisV,
This means it tries to download the background minipack over and over again. Can you open the dat/ folder in your installation directory and look for the core_mp01.lba/lbt/lbp files? Do you see any lbp or lbt? If so, rename them to .lba (if they both exist, rename the lbp, and delete the lbt).
Same goes with core_mp01_prev. Do you have a .lba file for it? Do you see any lbt/lbp files?
I will be at my dev machine in the evening and able to take a look, but I assume it would be some kind of local issue which was caused by right restrictions (lots of users are having this pack and none of them reported any issues). Alternatively you can try running the program as Administrator (start ePicGenerator.exe from the installation directory, and not the one on your desktop/start menu) and see if it can fix itself.
Let me know how it goes!