I get the message at start too, (win 7 glitch). It is easily ignored and the software is 99.9% effective. (I messed with .cng's a little and tried to rid the error message string, but it still comes up with a blank box. So I restored the orig cfg files.)
Why not make 100%, Acoustica? Somewhere in a dll or exe- there's a "find sound device string" in the startup batch. There is a trigger to this message if sound isn't found. (The program obviously finds sound eventually because the program works.) There should be an Update for Vista/7 users that eliminates the trigger for the error message string in startup. Let the "find audio device" fail without notification. Make a beta disclaimer that it's a quick fix and removes an error message- to cover your back.
Sorry got geeky on ya. But, I open the program so often, I am tired of the error. Thanks for a cool program.