Is it doing it with all saves from this module, or have you only made and tested one?
I've tested several saves, in different slots. Occasionally one will work, but most don't. I also tried starting the module with a brand new character to test if importing a character was causing problems somehow. The saves for the new character have the same problem.
There doesn't seem to be any pattern at all. I just loaded one save that wasn't working last night. Then I made a few more saves in the same map to test things out, and none of them would load, and neither would the save I originally loaded. Then I quit and restarted the game, and the original save was working again. So I made a quicksave and immediately tried to load it, and it didn't work. The whole thing is completely random.
Throughout all of this, I've made no changes to my NWN folder other than deleting a lot of old saves I wasn't using anymore, from other modules. I thought maybe having so many saves was slowing down the system somehow and deleting them might help, but it didn't.