After the software tweaking mentioned in the previous post, I was pretty happy with how it was running. A BIOS update got headless mode working with no other changes required; before the update, the Stick wouldn't boot without a display attached - just sitting there with the power LED lit but not doing anything useful.

I decided to leave it running for a while so that I could monitor for any memory leaks etc, and was rather puzzled to find that it seemed to die after sitting for about 5-10 minutes without any keyboard/mouse input (even if I was connected via SSH). The power LED stayed lit, but it didn't respond to any kind of input. I tried plugging the display, keyboard and mouse back in and booting back into the GUI, and found that it did the same thing. It seemed to be going to sleep / suspending itself, but I couldn't convince it to wake up - and no options I changed within the GUI seemed to change this behaviour.

I tried a few options found around the web (i.e. Ask Ubuntu), and eventually found one which works: set SUSPEND_METHODS="none" in /etc/default/acpi-support (and restart acpid). So far, so good!