Might be worth attaching your entire Renoise log file to a post Greg because there might be crash log stack trace information and what architecture (32 or 64 bit Renoise) that could help see what any AudioUnits/VSTs are up to. That error message seems similar to -> https://forum.renoise.com/t/osx-mavericks-audiounit-editors-do-crash/39442 from 2013 with Renoise 2.8 