errorlog.txt is to no use in finding out why something crash.
When a crash happens a crash dump should be sent and a dialog will be shown with a Crash ID.
Problem is that most of the time when a crash happens in 7zip it is in the part that come from the creators of 7zip, and if that is the case here, there is nothing I can do to fix it. But to find that out a crash dump is needed.
