I've been using an 861 for a while (v2, then v3, now v4), always controlled via an AMX NetLinx automation system.
I did have problems where, intermittently, when switching sources, I'd lose audio. I worked with Meridian (Atlanta), and by taking notes of things to try when it occurred again, Ken Forsythe was able to isolate the problem to a specific chip on a specific card. We replaced the card, and I've had no problems since then.
If your problem persists, but isn't reproducable at will, give Meridian a call and ask for help. If it does reproduce at will, that should be even easier to isolate.
By the way, I do volume ramping with the NetLinx automation system, and I can easily adjust volume as much as 10db/second in a high speed ramp. I have never, once, had a "system lock up" because of that. As the Meridian ramps the volume up (or down), I see a bargraph on my touchpanel showing where the volume is. It works like a champ.