Everytime I ran the game, it would start to lag about 30 seconds in, then crash altogether with a runtime error, no black screen with neat little error messages. Did some fiddling about, and removed a GrabImage command from my mapengine's SetUpdateScript. Problem didnt persist after that. Any reason why GrabImage can cause runtime errors? What is a runtime error anyway, and how different it is from the 'black-screen' errors?
You're doing a GrabImage every frame? Most likely you're running out of memory.