As I've mentioned a few times recently
I'm making a set of new Cheapo styles. Just today I was re-compiling them after making a large update -- new terrain, objects, standards, intro screen images, even sketches..... the lot.
The first three went fine, but when I tried to generate the ONML Snow style (I know, no great loss......), it loaded fine on the editor, all the terrain and objects worked fine, but as soon as I tried to load a Snow level on the game, crash.
[EDIT: Problem solved; see below.]