Title pretty much says it all. If I'm not using the computer, the thing seems to randomly shut down and reboot every hour or so. Sometimes, if the computer is sleeping, when I press on the keyboard or trackpad to wake it, it shuts down instead of opening up. It's never shut down while I'm using it. This is a replacement Mini - I returned the first because of the snow screen issue, and because it was randomly shutting down. This is the midrange model, upgraded to 2.6GHz, with 1TB Fusion drive. I upgraded to 16GB RAM with Crucial chips; I re-used the chips in this replacement. I don't know if this means anything, but in the Energy preferences panel, I selected the "Start up after power outage" option, so now the thing reboots up after shutting down. I don't know if that means this is a power issue, but I feellike it would be weird for the same issue to develop in two new computers, particularly when I haven't seen others reporting this. Any suggestions? Thanks!