On the first day of getting it and trying to play it, I discovered it would not launch. The launcher opens, I click 'play', then it flashes on screen for a second, before closing without a single error message. Pretty typical problem, right? Well, until you hear the rest of it.
I updated my graphics drivers, restarted my PC, then started the game. It worked just fine. I played for an hour or two before closing the game.
The next time I tried to play, it crashed in the same way it did the first time. This time, I verified the integrity of the game cache, and it worked. I once again played for a few more hours, before closing it and going to bed.
The next day, I woke up and wanted to play some more. So I attempted to launch the game, and it crashed. Verifying integrity of game cache didn't work, so I then deleted the .Ini files. The game worked. Played for another hour.
I did an experiment. I immediately closed the game, and attempted to start it up again; and it crashed. There was literally not a single second of time for ANYTHING to change. And yet the game crashed as though it were broken the entire time.
After half an hour of experimentation, I discovered that making it run in compatibility mode for Windows 7 made it work. I again, played for a little while. Closed it, came back later to play it again. It crashed.
After more experimentation, I discovered that DISABLING compatibility mode made it work. (I have never had a game IN MY LIFE that required me to turn off a setting to get it to work, when that VERY SAME SETTING got it to work in the first place!)
I haven't ever had a game that essentially breaks every time I close it, requiring me to fix it again. Typically, a single fix should work. The game runs just fine when playing, I haven't had any crashes while playing, only ever when trying to start it.
Due to this, I know it's not a hardware problem, otherwise the game wouldn't run at all.
At this point, I would GLADLY deal with in-game crashes if it meant I didn't have to deal with this. At least in-game crashes aren't GUARENTEED to happen, like startup crashes are.
EDIT (November 13th, 2015)
I'm convinced it has to do with the .exe of the game. I'm not sure why, but I have a feeling that something like the Fallout 4 Script Extender(once it gets released) will run the game just fine, due to the fact it uses a separate file to run the game.