Another staff member just returned from leave. This one is one of my "special needs children", as I think of them.
Special needs child: "The thingy has gone from the side of my screen!"
Me: "Sorry, which, uh, 'thingy'?"
SNC: "The thingy that lets you move up and down."
Me: "Oh the scroll bar?"
Note: At this point I made a mistake - I gave her far too much credit and over-thought the problem.
Me: "It's possible you might be able to turn it off and on. I'll have a look through the view options."
SNC: "It's gone from my list of emails and when I try to write a new email, too."
Me: "Hmmm... I'd better come look at your PC."
Naturally, I wanted to kick myself when I saw her screen: she had about ten emails, nowhere near enough to fill the screen.
Me: "Been doing some cleaning up?"
SNC: "Yes, I had too many emails, and somehow when I was deleted them, I deleted the thingy too."
Me: "Uh, no. It just vanishes when it's not needed. If you get more than a screen's worth of emails again, it will come back, I promise."
SNC: "But what about in the new email?"
I started a new email, then hit the Enter key until it was more than one screen long. The scroll bar dutifully appeared.
SNC: "Oh... I thought I had done something wrong."
You had, dear. You had. *sigh*