I have been having the same type of issue/s and have tried all the same help people have had to offer, in all the dfferent post I've read online.
To actually fix this issue I ended up having to go to the device manager and check for driver updates on all my devices, one at a time. I think the ones that had updates that fixed this issue were the ACPIx64-based PC under the computer drop down and the IDE ATA/ATAPI controllers, specifically the ICH ATA and SATA AHCI controllers (I think these made the difference). I checked them all, but these were the only ones that had updates. Once those were updated and the computer was restarted, it has stayed on. It's been on for a day now and no problems so far.