Another thing that happens is that users clear the PLC with the clear all option, not realizing that it wipes the IP config in flash. Since the cleared IP config doesn't show up until after a power cycle, they don't realize they've done it themselves.
CoolStoryBro: That's the exact reason that the default settings in the clear PLC dialog don't include the port setup. I did that to myself a half dozen times when we were developing Do-more...I was certain there was a bug in the flash. When I finally figured out what was happening (and it was quite the 'doh!' moment) we changed the default to exclude port settings.