This save shows the ghost of a dwarf who was not a member of my fortress (he was part of some raiding party?) who cannot be removed via slab (name does not appear) or burial even though I have his corpse in a stockpile. Many dwarves are dead at this point but even when there were many open graves the dwarves refused to bury the ghost's corpse. Fortress is crumbling because dwarves immediately cancel any tasks with the ghost nearby. They even cancel eating, drinking, and sleeping resulting in insanity.