I'm sure everyone must have seen this.
"Help! all my typing has disappeared."
Go to have a look. An empty page greets me.
"What did you do?"
"Well I was working on this proposal and the phone rang, so I answered it.
When I turned back all my proposal had gone."
"How much had you written?"
"I was on page 3."
Then I pointed out that she was on page 99 (or something equally large) and that if she rested her notebook on the enter key again it would add on a few more empty pages for her.
Deleting the 96 odd empty pages earned me a rather nice Almond Magnum later in the day.