For those unfamiliar with automated warehouses - the single mechanical component that does most of the work is the crane, a huge robotic arm that travels up and down the aisle, storing and retrieving trays on demand. The crane has some safety features installed, one of which is height control. The software on board the controller knows the maximum height of every tray in the system, and you cannot move a tray back to its rack if it's too high. How does it know whether the load is beyond limit? A special photoelectric "eye" looks above the tray as it travels into the aisle, and checks its height. If the tray is too high, an alarm sounds, and the tray is returned back to the workstation. The warehouse person is alerted to the problem, has to fix it, and tells the crane to store the tray again.
In that particular warehouse the soldiers encountered a very common problem related to height control: some trays had plastic bags in them, and the bags would often stick out of the tray, triggering the alarm. The tray would then slowly return back to the manned station, and work would be delayed until the warehouse person shoved the rebellious bag to the bottom of the bin. Sometimes the alarm got triggered several times in a row. Eventually they got tired of this "safety feature" and decided to glue the robotic eye shut. For a while everything went just fine. The tall trays passed under the eye undetected, got stored in the racks, and the plastic bags were neatly crumpled upon entry to their respective cells. No harm done.
Until one day, the soldier who operated the loading station made a little mistake. Instead of having a bag protrude over the tray, it was a pile of steel bolts... Again, the blindfolded crane passed the tray into the aisle, and then attempted to store it back to its place in the rack. At that point the inevitable happened - the bolts refused to crumple. A huge collision. Damage to the crane, damage to the engine, damage to the rack and tray. A short investigation revealed the glued "eyes". People were thrown in jail for a few weeks. Enlarged photos of the accident were hung on every wall in the warehouse.
Moral of the story? Keep it safe, people.