I wonder how that will do in the end. But at any rate HDDs stopping is a fairly common issue they have, can be mobo releated, sata controller related, hdd firmware/driver related, typically is simply the OS power saving option. You'll need to go over all of these. To be doubly sure it's not your HDD, you will also need to run some prolonged tests on it.
But all that could be for nothing if it's a bug with the game. But on that, the game would not be causing the HDD to shut down, it would simply not be sending out a message to the system to not go to sleep... something you advised you already unselected... so unlikely at best.