Most of the time, video games work like they're supposed to. Most of the time. Sometimes, though, they don't, and sometimes, the way they don't can be horrifying.
These bugs and graphical errors on PC games go beyond the annoying or frustrating. They're not the kind to just crash your game or freeze up your PC. They're the kind that give you nightmares, wondering when you'd signed out of Windows and signed into the realm of Gozer the Gozerian.