I don't know.
I have tried it more time. I am pretty sure that there were nothing in the directory before.
I know that I had 2 times the same problem. I had uninstalled VDF16.1 each time before.
When I read the message of Roel, I checked all .exe files in the bin directory and only the dfcomp was checked.

I don't know if Windows 7 remembers which file have to be in compatibility mode for Windows XP SP3.