Perhaps you could have a look at this thread:
http://www.opserver.de/ubb7/ubbthreads.php?ubb=showflat&Number=305715#Post305715

Basically game_load() fails for me under certain circumstances, when I try to load a path that was modified by path_setnode().

The problem only occurs if game_load() is used after closing and restarting the engine (without changing scripts or other game related resources in between). If path_setnode() is not used, game_load() works fine in any case. I don't know if the same is true of path_setedge(), though.

Perhaps I'm doing something wrong, but I'm tending towards thinking this might be a bug.