A while ago, I recall Angry Technician discussing how he had a chronic case of "The Ear," an ability to walk past any machine, stop and instinctively know something is wrong and require fixing.

I had such an episode today dealing with tick grids for the end of year process in SIMS. I believe they call it curriculum assignment but after a while, hours of ticking boxes against a list causes the brain to melt slightly and simplify the entire system down to "Tick Grids." And I had a feeling that said ticks would disappear on me all of a sudden so I saved. Nice, half a year group later I save again:

"Unable to save data. The curriculum structure has changed since last load."

Then the tick grids go blank. Me and the boss learned a hard lesson today, never do curriculum assignment and send the timetable to SQL at the same time.