EDIT: Thank you all for detailing your experience with, and hatred for, this miserable product. Your display of solidarity is inspiring. Now, say it with me:
It temporarily deletes my meetings just before they happen, so that I don't have to attend them!
Of course, when I open it later, the meetings are restored, with the original date, and no trace of the deletion. So not attending them is quite hard to explain to others. But it does save me from attending!