CRTs and Backups
Fun times were had when a team of software engineers kept getting corrupted backups on a Sony DAT (remember those?) so off to the repair shop it went. The shop couldn't find anything wrong but the team's backups were still being corrupted so the DAT, cable and controller card were bundled up and sent off. No errors detected. Then they asked me to have a look at it and I spotted the problem right away. They had laid the cable connecting the controller card to the DAT across the top of a 21" CRT. Cable moved, problem solved.