... when it's a problem with the game engine.
I had an accidental breach of a cavern while there were a couple of Forgotten Beasts in there. I generally leave those alone, since there's really nothing in the caverns I can't get by tunneling elsewhere. So it's not uncommon for me to have a couple of Beasts roaming around in there with nothing to do.
I sent a squad of steel-equipped dwarves down for security while I sealed the breach. They killed the first beast easily, but the second one simply would not die. It was a "blob" with a body and two wings, and apparently it doesn't matter how much damage those take, it won't bleed and there's nothing vital. Wings and body were "fractured" and "broken open" 20-30 times each, but it still kept fighting and eventually killed a couple of the guards.
Meanwhile, I walled the cavern off... and discovered that half of my dwarf population had wandered into the cavern. The way slopes are in there, it's often hard to see what's going on since each ground level is pretty small. They all seemed to be "storing item to stockpile," I'm not sure what.
By this time the blob wasn't too mobile, so with some work I rescued a fair number of the idiots, and walled the corridor off further back since the blob had chased some into the shafts. This is where the not-fun part comes in.
There were some that I couldn't rescue, and apparently that was screwing up the job assignment logic. A lot of tasks like digging, hauling, and construction would no longer resolve. If I had to guess, the game was assigning tasks to the doomed dwarves, and then dropping them when it proved impossible for them to path to the job site. I ended up abandoning the fort. I could have lived with the losses, it was the fact that lots of critical other tasks weren't being done due to the game not handling this well that made it seem like a waste of time to continue.
In retrospect, if that was indeed the problem, maybe I could have fixed it by turning all the tasks (including haulage) off for the stranded dwarves. It's OK, I guess, the fort was too stable and boring and that point anyway - I got into trouble in the first place because I was constructing a magma pump stack from level 7 to level 120, and I dug into an unseen cavern on the way up. That's the sort of project you undertake when there's nothing much else to do.
- Gus