I used to work second tier customer service for a catalog based retailer. I had pretty much always worked second shift, which was a 2-11 time slot. Our IT department insisted on having all virus scans (network base) run at the same time during the day, which meant it was scheduled to run after 5 pm (so the sales department wasn't affected), during the busiest part of my shift. It got to the point where I would have to do a hard shutdown on my machine (yeah, bad form), but it was the only solution I had to stop it from running (it wouldn't restart when I powered back up). My PHB saw me sitting idly at my desk looking at a blank screen and asked what I was doing, and after explaining this over a two week period, the IT guys eventually rescheduled my scan to run in the morning.