Sorry to bring a dead thread back to life, but I've been having this problem with my game and I'm currently attempting to reinstall after removing all mods and whatnot. I've tried most of the stuff already posted in this thread, but I still keep getting the crazy shadow transitions and the gridlines... Graphics card is ATI Mobility Radeon HD 4250...not that great, but I'd like to know if that could be the reason why its continuing or if there's a solution that hasn't been posted yet.