Need help - CAW no longer Exports the World I'm working on.

It does seem a temperamental bit of kit. Have you thought of posting under Game Tools. There are quite a few experienced world builders there who have probably come across this kind of thing quite often. I find my large store content causes issues and also rembering to delete earlier versions I have exported to the game. Version control helps with this and remembering to keep a back up of the earlier version you most wanted to keep :)