I saw this first hand when I was overseeing the crash reports during the release of an online AAA game. A game with millions of players.
A fairly frequent crash bug was caused by a line with a comment explaining that it could theoretically cause a crash but that risk would be one in a million.
It only happened on players connecting or disconnecting from the server. Unfortunately it was a server crash so once it did occur it discontented up to eight players.
