I've noticed that when Sonar Platinum (October update) starts up it seems to hang if there is a USB interface available that doesn't respond. It loads the project, shows the tracks then hangs. When I turn off the USB interface it starts correctly. I don't know if this is normal behavior because I've only recently added a USB interface. I've noticed that when Sonar is running and sees the I/O come online it asks if I want to add it.
 
However, my situation might be a little different. I have a Lynx Hilo that's connected to both an AES16e PCIe card and to a USB port. When the Hilo is switched off Sonar starts fine. When the Hilo is on and in AES connection mode Sonar hangs opening a project.  This seems to indicate that when Sonar starts up it expects some kind of response from available USB ports that are powered up (if that's the correct expression) and hangs if there is no response (instead of timing out). On the other hand maybe it's a Hilo firmware bug if perhaps it's ignoring the USB interface when it's in only-AES mode.
 
I don't really know where to go with this info, but any comments are welcome, and I may raise the issue with Lynx support in case it's a Hilo issue.

I think you're right, SONAR is waiting (forever) for a response from the driver, which in turn is waiting (forever) for a response from the USB port. The interface has disabled the USB port, and that's the device SONAR knows about. The AES and USB interfaces are two separate devices as far as Windows (and therefore SONAR) is concerned, so from SONAR's perspective it's looking for a device that no longer exists.
 
Maybe the easiest solution is to pick one mode and stick with it all the time, assuming that's possible.