Ok so my vault is upgraded to the maximum, 200 dwellers. I had bought a bunch of lunch boxes and had forgot to open about 20 of them. When I did I won a ton of new dwellers... What to do now? I know most people send them out to the wasteland to die but most of my dwellers were a pretty decent level and I didn't want to wait that long. So I decided to create diners, (cause they're cheap) on floor 25. I put the unwanted dwellers in there, stripped them of outfits and weapons and rushed the rooms until they were dead. I removed the "corpses" and added the new people. I kept the 25th floor for this reason only. To kill off unwanted dwellers.

After awhile I was running low on food so I staffed a few dwellers in the diners. That's when things got weird... First I noticed when the rooms were ready for collecting and I tapped the food symbol the diner workers would go up the elevator, through a couple rooms and then back to their original positions. They were not walking slowly like they were on a coffee break but quickly like I had assigned them to a new room. I thought to myself maybe I accidentally dragged them to the diner in the adjacent rooms. But they always returned to their original positions. So I began to observe them.

Sometimes the dwellers would -at random- run to the next door diner and abandon a whole room and then run back. Like they were trying to get away from something. I noticed them doing this quite a bit. I figured it was a bug in the game from having a full house and every floor space built. I thought maybe I was about to crash the game or something. But it seemed to happen quite a bit.

I would also be playing and suddenly the diners would go completely dark. Like there was not enough electricity but the meter would be close to if not at maximum.

So eventually I started really paying attention to the bottom floor... The diner workers did their crazy run away thing and I quickly clicked on the abandoned room. I saw a puff of smoke, similar to what comes out of the fire extinguishers but it rushed from one side of the room to the other! After it was gone the diner workers came back like nothing happened. I, however, was totally freaked out!

The final straw... I was collecting from the lower level and noticed the workers just standing weird after I collected the food symbol. I was zoomed out almost all the way but I quickly double clicked on that room to zoom in and every worker in that room had red dots for eyes instead of black! I quickly zoomed back out and in again and they looked normal.

I couldn't take it anymore so I stripped them of gear, sent them all to the wasteland (like I should have done to begin with) and deleted every room and elevator leading to the 25th floor.

I don't know if this was a glitch or what but I was so freaked out I was scared to play the game for like 2-3 days. When I finally got up the nerve to play again everything was back to normal and I have had zero trouble since. My vault now has 1-24 floors and will stay that way permanently.

Gotta equip your peeps with plasma rifles if you want them to work on that floor:D