Hi everyone, I'm facing an issue with a 2011 MacBook Pro (i5). This is something persistent, I can't define a exact time to happens but is a "normal" behavior. The problem I'm facing is basically this: Without any previous identified error or problem this Mac in one random occasion after shut down while power on (booting screen) shuts down and can't get any way to make it booting properly again. First time this happened to me I formatted the internal drive, installed the High Sierra (happens as well on Sierra) and install all my software from the very first beginning (didn't recover from Time Machine to avoid any possible software problem). After one or two days later after doing a normal shut down try to power on and stuck with this problem. It's the third time I reformat the computer and always with any specific action from my part this happens and I can't understand the problem. I run a Diagnostics test from USB and no error found. If I want to boot from any OS X USB installer Mac works fine. Track pad, keyboard everything working fine. I also try to check my boot drive (have two ssd's installed) and when run first aid process it can't go thought and give me this error message: "First Aid process has failed. If possible back up the data on this volume" (error -8). Reading this error message I assume that maybe have a problem with the boot SSD but it's a bit weird because both SSD's are completely brand new. I will try to install OS X on the other SSD and check if have this issue too. If someone already have this issue or know something about it can please give me a little help, to make sure I', doing this properly? Sorry for my English. Thank you! EDIT: also try to do SMC and PRAM reset and didn't help.