EDIT: I changed HL2 to HL2_old, and for some reason it works again.
I haven't quite been able to find people with this problem or how to fix it. Amnesia runs perfectly fine for me, and my graphics card is a GeForce GT 240 (Nvidia), which is a more than sufficient card, and I run more detailed games at high settings with ease.
The problem is this: I downloaded the level editor for amnesia. Yesterday it ran fine, (aside from the program window being insanely large relative to my 1024x768 screen*), but out of nowhere whenever I try starting up the level editor I get a black screen and then a message saying "Fatal Error: Renderer #0 could not be initialized! Make sure your graphic card drivers are up to date. Check log file for more information".
Meanwhile, the model and particle editors work just fine.
1. That's still an issue with me