My Endnote Library.enl disappeared in Endnote20

Dear All:

        After I installed Endnote 20, this problem happened 3 times. I did nothing wrong, Turn off the computer, and the My Endnote Library.enl file disappeared from the folder after coming to my office the next day. It happens on both my laptop and desktop. Luckily, I was able to recover it using my backup file. However, since it happened 3 times, I think I better report it.