Audio Engine Dropout -- Sonar Platinum

I have 2 reverb stereo busses on a project.  I have sends from other busses going to these reverb busses (Using ReMatrix Solo).  However, whenever I add one or both sends to these two busses from one specific buss, the audio engine will drop out (sometimes even before I press play).
 
The buss with the sends that is causing this problem has the following ProChannel modules active:  FX Chain with an instance of Amplitube 3; EQ; Console Emulation.
 
I deleted the buss with the sends and started over.  Still get audio dropouts (but the audio engine hasn't stopped, yet).
 
I have the latest Braintree updates installed.  This project was started in X3e.
 
Any thoughts on why this could be happening?  Please let me know if you need any more information.
Thanks,
 
 
Paul