When I came back four hours later, the thing had rebooted itself. For no apparent reason.
I think this is the second or third spontaneous reboot since loading Ubuntu a week ago Friday.
SOMETHING ain't stable. I don't know if it's the OS, or if long-term hardware problems that Windows just dumbed over are becoming more evident. After all, if I'd come back to a spontaneous reboot FNAR when this thing was still running Windows, I'd just have muttered something nasty about Microsoft.
I was HOPING that most of the hardware problems were centered in the 9-year-old hard drive that I yanked, but no such luck.