I've noticed that the saved game gets corrupted more often if you play for long time, without saving/exiting. It might be a memory leak issue.
Before I even knew the issue existed, I was saving my game at any condition (in the port, during the convoy attack, evading a DD...) and never had any problem. A month ago I returned to the game, installed GWX and started playing for long periods of time
. I found out about the saving issue, and started to watch when I save, and yet I had a few CTDs after loading.