[justinhill]

I have no idea if my experience is anything to do with this but... after my system suddenly stopped randomly falling over with 9173s the other day and went back to working normally I decided to shut it down for the first time in several weeks yesterday so I could hoover out the cooling intakes at the bottom of the machine, which I could see had some fluff building up round them.

To do this I had to unplug all the cables of course. After I plugged everything back in again the Mac would not boot. Repeated attempts to get it started got me nowhere. It would chime but go no further.

In the end I got it working by connecting just one display and no other peripherals at all, then adding the other displays, external storage, audio interface etc one at a time without re-starting. I haven't dared shut it down since.