Thanks for the help.
I did install it through Steam (once I figured it was the online key I needed to use, not the serial), it's running perfectly fine, I did a few practise races.
I made a copy of the steam install, the AutoUpdater is currently reinstalling everything.
Hopefully I'll be able to join a race tonight.
(I tried beforehand compatibility modes and run as admin: compatibility changes nothing, and the game definitely won't start with admin rights. Really weird.)
edit: Hello Bordi, nice to see you still there.
