I'm having the same problem here, only once Fusion has crashed, it crashes even after the Duet has been unplugged - only a reboot fixes it.
This is a pretty major problem for me, as I swap the soundcard in and out fairly regularly. I can try quitting Fusion whenever I need to use it, but having to reboot every time isn't ideal.
Is there any way, having purchased an upgrade from Fusion 5.x to 6.x, of downgrading until this has been fixed?
Or alternatively, any workaround?
Thanks.