PUBG is crazy unstable, you are not the only one who is experiencing these crazy drops or game crashes causing you to restart pc.
What I used to do (every since the new update mine does not crash anymore, it only lags out for a bit now, while before it would crash every 2-3 games mid game, before a game started etc.) was ctrl alt del, then sign out and sign back in.
I hope that since you posted this that you are not experiencing this anymore, as they have done numerous amounts of fixes