It's happened on different episodes, I think its more about runtime than the episode. And I'm not sure but I think it's on all the servers, I just tend to join the one with the most players.
Thanks for responding so fast, sorry for the vague ish answer.
Edit: Oh, another solution like allowing mapchange would be for it to save the map it's on so if it does crash it automatically sets the map back to the one it was on, of course this would require a mod and I can see it being rather difficult. Nevertheless, it's not a perfect solution but it would still help a LOT. (if it's possible)