Same problem after having cleared a huge vault in Tol Falas. Something in the code simply can't handle too many actors (monsters or objects). That's why I never save in dungeons, but always on the surface. If something goes wrong when loading, you can simply delete the corresponding zone-xxx.teaz file and start with a brand new zone.
[tome] joylove: You can't just release an expansion like one would release a Kraken XD
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[tome] phantomfrettchen: your ability not to tease anyone is simply stunning