So I got the DRM-free Witcher 2 EE, downloaded, installed, and played for a bit, saved, quit, and came back later. Still worked fine.

Repeated the above a few times, and suddenly it refuses to start. I put about 5 hours of gameplay in before the typical '0000005c' error message started happening.

Now I'm not an expert, but I don't think that an installer file corruption would cause a game to work and fail afterwards, so could I get some help here?