New enemy crashes one map, but not another!?

[Your Computer]

Only the editors make use of the editor configuration files. The game itself doesn't need them, therefore doesn't touch them. If that's all you see, then you're looking at the wrong hpl.log. A proper hpl.log would show you information about your hardware, the resources the game creates, etc. I've never created a custom monster before, nor have i modified any existing monster, so unless i can get some technical insight i don't think i'm going to be able to help you. Maybe if you send me the modified monster, i could probably then see if i can get something out of the log.