rpmartino -
Do you happen to be using the sidechain functionality? Just to see if it solves the problem, try setting the MAS sidechain channel (under the Tools menu) to some unused bus number and see if the error goes away.
Thanks for the info - I inserted TrackPlug and re-set the MAS sidechain bus. It apparently defaults to Bus1 which I was already using. Do you know if WaveArts changed something in their update which caused this problem? What will probably do in the future not assign bus1 in my work as a means of avoiding this. problem. Again, many thanks. Greg Jones