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.

Thanks for the report. I've tried to reproduce the problem, but don't get a load error with my test path. Can you contact Support and email them your project, with the WMB and WMP files? They'll look into this.

All right, I've sent the project to the support today.

Thanks for the project! It was indeed a bug, and will be fixed in the next update.