There's so many possibilities to why this is happening. Most of the ones I think of are silly but could be useful to know.
Perhaps a certain mod we've got could be the cause whether we got it this week or a while back. Or we may have too many adding for modter. I built my map in single player before making it multiplayer... But I can only just it on single player or multiplayer, not dedicated. Perhaps the save is corrup, or the pc may not be able to handle it. I think this because my of is crop and today I tried something didifferent. Instead of loading it and waiting which crashes blockland, I loaded it then quickly left. The results were the same as when I've crashed once and I'm tried resetting the game, it just let me spawn then crashed. I reckon it could be a vehicle glitch. I have a vehicle that crashes my whole game and crashes me after spawning when rejoin. I'm sure the vehicle is a plane or tank: T-90 or A10?