We had a similar one when I worked for a large supermarket chain. We had one store that their In-Store Processor (ISP), which was a big IBM 6F1 RS/6000 box (ab

We had a similar one when I worked for a large supermarket chain. We had one store that their In-Store Processor (ISP), which was a big IBM 6F1 RS/6000 box (about the size and looks of a large mini-fridge) was plagued with all kinds of weird and sporadic errors. Code that works fine in the rest of the chain would only sometimes work there, all kinds of disk errors, slowness, etc. We sent technicians to the store multiple times and they could never figure out the issue, we even swapped out most of the hardware. Eventually, we discovered that the young girl that was responsible for changing all the prices was using the server room as her makeshift office. She would stick all her magnetic clipboards with the upcoming price changes to the side of the server. When she heard the tech was coming she would clear out all her stuff since she knew no one was supposed to be in there. The magnets were wreaking havoc on the disks causing the errors. The store manager got her some proper office space and the errors went away.