Same thing and yes I have win 7 64, but it is all the same even when I install the game in my main dir not my slave dir. I still get the same thing. I am going to try my girlfriends computer that has XP still on it. I even used compatibility mode and ran it as admin and in xp SP3 still the same.
Edit: same with that computer as well. Very odd, but at least on that computer the warning read what CPU I am using.