This happens to me as well. Usually during the early laning phase I will crash once per game only if I'm partied with a steam friend. Once the crash happens, it kicks me out of the party so I'm fine the rest of the match, but I will have to rejoin party to queue up again.
As the title says, every single game I play while partied with someone on my steam friends list will result in my game crashing exactly once per match. I can go weeks with no crashes, then one night play with a friend at it will crash every single game. Took awhile for me to catch on to this...