Frostyfrog

@Geoffrey, Yes. I understand all of that. It used to be that when you spawn or join, Minecraft would find the closest 2-high set of airblocks above you (if you're in solid blocks) and place you there. This no longer happens, and IMO, is the cause of the issue. SSP is SMP (well, it is basically now).

And besides, a group of people could be landscaping where you are standing. And instead of standing in a plains biome, you are now suffocating inside a mountain. 😉 No malicious intent at all.

I'm pretty sure this is related to the spawn/join protection being removed (or reimplemented in a different fashion?). If someone fills an area with stone (for example) while you are offline, then when you join, you will be in the blocks and taking suffocation damage. If the old join code were added back in, I'm pretty sure it would completely resolve this issue (and make logoutivators possible again, but some people like that part!).