I was busy working out a spreadsheet with my students' marks on it. I had been working on it for about 45 minutes to an hour when I figured I would save it and then print. I needed to save it in a different format so that I could read it at work, but when I selected that option, it told me that the earlier format couldn't read all of my formulas. So I hit cancel, which I thought meant cancel saving it in that format, but what it cancelled was saving it - it just closed it without saving!
So, I have just spent a second 45 minutes to an hour reinputting the data. This time I was a good girl and saved it at regular intervals throughout the development of the spreadsheet. I also printed out a copy. However, I hadn't really wanted to do the whole thing twice. After all, how badly did I really want to learn patience this morning?