While exploring in both transferred and new worlds, the client (or server) will randomly lock up and close. Single player does not yield a crash log. I do not know if the multiplayer crash is the same as my single player worlds, but the single player crash is repeatable on my end.
The crash log from the server (from my understanding of it) does not seem like it would be the same error on single player, but I can upload it upon request.
Please attach the log here.