Mid 2011 model. Hard drive finally giving up, so I bought a Samsung 860 EVO SSD. Installed, and did a clean install of High Sierra. Came home yesterday, woke the computer from sleep, and it rebooted several times before booting to the login screen. Everything works great while I'm actually using the computer. Today same thing happened upon waking the computer from sleep. I later noticed that after it was asleep for a while, it would randomly reboot on it's own as well. Everything works beautifully while I'm actively using it, the issue seems to only lie with the sleep/wake process. Any ideas?