I too get the same message but I get it after many sucsessful playings of CIV4...
I shut down the game two days ago after saving mid game and have not been able to start CIV since then... I get that darn message I try to start and have no idea why....
I could understand if I had changed settings, or installed new programs, but I tried restarting after just a few minutes and got this message....
No, I don't have any programs like Alc 120% or anything like that...
Help!