From what I read on the official forums, this bug tends to affect people who are continuing a campaign from version 1.3 or earlier. Certain historic events cause the crash. I haven't experienced it in my saves or campaigns since 1.5 though.

Removing the event from the descr_events.txt file apparently does nothing, because once the campaign has started and the file has been read and the game saved, it doesn't reference that file anymore. Or something along those lines.