If it isn't a corrupted save file or Oculus/SteamVR interference, then I'm not sure what could be causing the issue. It makes sense that neither of those things are causing problems, as I'm sure I've integrated fail-safes for both of those things in the current build, but I haven't heard of an issue with an unwarranted black screen without any prior gameplay. I'm sorry I can't help more! Hopefully it'll fix itself with the next update.