I find crashes to be quite rare in the last year or so.
I have a computer that is five years old with a slow processor and often lots of problems.
Several things you can do that seem to help (real computer experts may tell you some of this is nonsense, but it works for me):
Before you play a game, clear the cache.
Close all other windows.
Avoid playing when you are likely to be interrupted.
If the game slows, hold off on inputting new commands until it catches up.

If the game does crash, you will NOT be able to play the next game until you have contacted Tech and had them do a reset.
Under the rules, a crashed game can be finished by the robot by tech, and even replayed until the home team loses. In my experience, this is seldom enforced except for a playoff series.

It is correct that an incomplete or messed up lineup by the away team can cause the game to not open. This is why it is so important that all active managers keep default lineups and pitching selections saved and update them occasionally to correct problems due to injuries or usage.
Tech and the Commish have to set these for the unmanaged team, which is part of the reason there are sometimes delays.

Dave N