A couple of weeks ago I wrote this haiku:
Thirty tabs had I
Closed the window, but not all
Now I have just one
A very common plight in our modern browser age, at least for those of us who are tab fiends. (I regularily have 20+ tabs open at a time and depend heavily on Firefox to remember what those tabs are) Browser crashes, or more likely, you accidently close a browser window with all your tabs that you thought was the main one, but it wasn't, and now Firefox doesn't have a record of what you had open. Painful.
Yes yes, I probably should not have that many tabs open in the first place, for issues of focus and productivity and "getting things done", and also for performance reasons, but let's ignore that for now.