Pretty simple. I made a boss script in a sideview screen that could shoot fire weapons at very high speeds (800 to 1000) at the open right side of the screen. Consistently when the fires were going too far off the side of the screen, the game would crash. I tested with shorter ranges and them falling off the bottom of the screen and it didn't crash. Guessing this has something to do with the fire weapon's unique death style and it not playing nice with it going past the offscreen kill distance.
Tested in 2.53 release 2.