Hi all
I was doing some recording yesterday and plugged in my recent purchase, the Yamaha MX49 to use as a controller.  Big mistake.  In addition to the Sonar audio engine stopping, a quick look in preferences showed no "audio recording and playback devices."  After exiting Sonar, I opened Reason; it worked fine.  VLC media player had no problems.  Re-booting the computer and soundcard (Roland Octa-Capture) didn't fix the SONAR issue until I disconnected the Yamaha and then rebooted.  Then, the Octa was visible and available.
 
A half hour or so of my recording session wasted, and a considerable interruption of creative flow. I don't need a solution, as I'll just keep the MX away from Sonar.  I'm using Sonar Platinum, 22.5.0 build 45  x64
 
LJR