I'm such an idiot. My office has windows and a door (obviously). When the wind's blowing, the unequal air pressure sends things flying.
Today, what went flying when a colleague walked in was one of my framed pictures. What it hit was my lovely Apple MacBook Pro. Terrible cracks in the glass and a dent in the body. The machine's still working, but I' m looking at £150+ repairs. I'm such an idiot. What a waste of a large amount of money. Looks like the book diet's back on.