(As a side note, I tried to attach this image to the post and got a forum error message about “cannot find attachment directory” or something to that effect).
I was raided by dwarves quite a while back, had them caught up in my entryway, and kicked their butts. There were dwarf corpses, along with whatever items they dropped, caught around the inside part of the entrance and in between each of the entrance doors. I commanded my imps to fetch all of the items in this area, then dispatched them to get all the goodies. That was probably about 3000 turns ago (just guessing at that number).
The imps did exactly what they were supposed to do, but two of the tiles (the ones between the doors) are still “dispatch highlighted”. It hasn't seemed to mess anything up at all though, and they've fetched/dispatched appropriately to all other sorts of things around the map.
UPDATE: 6 hours logged. Crashed a couple of times, but it sent an error report. Happened during battle with knights.