Yeah, that's the same issue I was referring to on windows a few pages back - It was supposedly fixed but for some reason its very elusive.
You can try starting with -zapwallettxes=1 first, then tell me if it happens again.
If not I will try to reproduce it, but I have not been able to reproduce it on my dev ubuntu box yet.
Note, if you have time you can run your wallet in valgrind and see if a stack trace is created.