Well, there is the exp change for Ninja that is save-incompatible, but that shouldn't cause a lockup, you should just still have any Ninjas from your saves level up as elite. Did you try an earlier save & running up to the point of the freeze? Maybe we could isolate a point in your game when the cause of this bug appeared. I could use your saves to experiment...
If you have the pagoda preview installed it may be some weird pathfinding issue or maybe simple overload for the engine? It IS a bit wonky on different machines after all.
I want to have the two complete areas ready for the release. Within a week there will be a release candidate of the basic (no-new-content) version. I'll start a playthrough and will appreciate anyone else doing so and reporting anything wrong.
And if anyone makes a sensible sub-mod, I welcome it as an optional component. For example most of the doable class changes are very easy to do, same for item and monster stats or placement.
There is one pretty common criticism of Wiz8, which is tedious amount of combat and possible remedy for this.
This is actually quite controversial change to do. Less combat means you will be sorely underpowered for most fixed opponents. Faster exp gain doesn't cut it, as the main benefit of frequent battles is skill growth. Which means some kind of "easy mode" would have to be included.
Again, new areas should solve this need for training naturally. Skeletons in the crypt will mean less poppies on Arnika road.