I installed Windows 8.1 from Windows 7 a few weeks ago, and have since had to reinstall THREE times because of this same error.
Basically, after a few days of normal use, I start getting "Shockwave Flash Player has stopped working" in google chrome, firefox, windows apps, etc.
So, I go ahead and try to restart windows. Shuts down just fine. But, it wont start. I now get the automatic repair, which doesn't work. Error code i'm given from the BSOD: 0xc000021a. Safe Mode does not work.
Some programs i've had installed: Chrome, Photoshop, Firefox, Trello (Windows App), Java, SublimeText 2, FileZilla, Skype, and a few others that don't come to mind.
Any help would be greatly appreciated. In the mean time, I'm using Ubuntu.