Jean-Pierre...THANKS now the F 40 growls again!Surely a corrupted or missing file.
In Steam, right-click your AC game, choose 'Proprieties', Local files tab and click "check integrity of game cache".
If a file is missing or corrupted, it will be downloaded again.
Try this first.
Just a notice for you Roca ... am I still your "angle in the sky" ?? ... my avatar should give you an idea of my pseudo somewhere else.
Edit: angel of course and not angle !
I'm not so ... sharp in fact.