Problem solved. Corrupted preferences files which I've deleted and replaced thanks to advice just received from Audirvana customer support.
If this happens to any other "Audirvana Legacy Users", here are the terminal codes to correct the problem:
defaults delete com.audirvana.Audirvana-Plus
defaults delete com.audirvana.Audirvana
After that's done, you'll need to re-enter the license code.
Keith