The last time you opened LibreOffice, it unexpectedly quit while reopening windows. Do you want to try to reopen its windows again?

Whenever I open Libre Office, which I have tried updating to 4.0, I get this pop that says “The last time you opened LibreOffice, it unexpectedly quit while reopening windows. Do you want to try to reopen its windows again?” I can not close it. Both buttons do nothing. I have restarted my computer, and this have never happened before.

Duplicate of Can't close pop up window