Sometimes map makers are idiots or morons and make silly crap in their maps. Still, their maps make it in into the world without the map makers ever correcting their maps. Without the need to redo a map or save it to a new file, some bugs can be corrected during runtime (not too many though).
However, this mod corrects some minor bugs on maps (see below), just run it, and keep your maps untouched.
Here's the download link for convenience.
http://aliens.gamepoint.net/mods/WAMapBug_03.zip