Another thing I noticed (I don't have enough emails saved to be able to verify
this, as I unsubscribed from a mailing list I was on for a while)...
Try setting the view/message list/aggregation to standard. The threaded views
seemed to be problematic, causing these mysterious crashes and program quits.
Again, I cannot actually verify this and I don't have any threaded email
correspondence saved, so I am not able to verify the problem, but standard view
seemed to minimize the problem for me.