Last night and this morning, I helped two coworkers work through problems with an internal tool that I happen to have written the internal documentation and training for. It looked to me, from what I was able to see in the logs, like the problem was user error - both of them were, completely separately and independently, doing Operation X instead of Operation Y.
Which really made me think, "Gee, how crappy must my training and documentation have been, if it left them so confused? What the hell did I do wrong?"
Until I asked the second colleague, "Hey, why did you do X instead of Y?"
And she replied, "Oh, Y isn't visible in my user-interface."
It's looking like the tool administrator borked up a bunch of people's permissions. Fortunately, my documentation covers what to do in that case.