I upped my VRAM from 512MB to 1024MB and it seems to work now. Isn't that a lot?

That is strange, that might have something to do with some special access rights configuration.
Yes, I was also thinking that. So I tried installing in C:/temp/ but it did not help. Then I tried manually assigning extra rights to the folder, but it did not seem to help. I also tried running the ...

The problem seems to be the installer. I used the zip package and now it's working.

I just reinstalled the demo and it's working like a charm.
Then I reinstalled the full game and it's not working again.

I just bought the game after playing the demo without any trouble, but now the full game won't start:

22:42:36 Info None: 2014:11:22; Factorio 0.10.12 (Build 10773, win32)
22:42:36 Info Mods: Loading mod core 0.0.0
22:42:36 Info Mods: Loading mod base 0.10.12
22:42:37 Info Atlas: Initial atlas ...