So I use two monitors, and I haven't had a problem at all. However, today I went to play a game on Steam with a friend (Space Engineers, in case that's necessary), and while it was starting up, I had to update a Microsoft .NET file.
After doing that, and restarting, my main screen no longer displayed. I've tried going into Safe Mode (Which starts on my main screen and displays without a problem) and uninstalling/re-installing the drivers to no avail. The screen will display when booting up, but then when it gets to the lock screen, it turns off and everything moves to the second screen.
If any further details are needed, please let me know. I've tried talking to Microsoft online support, but that was a joke and a half.
EDIT: My PC managed to fix itself overnight. Not sure what changed, but hey, I'm not complaining.