I am running a multiplayer server. Everything is plain vanilla directly from Mojang. No mod, no texture pack, no third party anything. 100% standard.
Besides the usual random bugs (dogs disappearing, ...) everything was fine until a few days ago when a section of the world stopped "working". Players noticed because it happened in their house, where their chests were. In this section, we are unable to open a chest, place or break any block, torches, anything at all. We are still able to move freely around. The problem extends whatever "height" we are. Near bedrock level, we are still unable to break any block so this seems to be related to that single particular chunk.
The problem occured when we were in 1.5.1. The move to 1.5.2 didn't fix it.
It then becomes interesting:
I copied the world folder content on my Save folder (for single player games) and if I open the world in multiplayer EVERYTHING IS FINE. Chests open, I can break blocks, remove torches, place new ones. If I copy the folder back into the server's world folder, I get to see the alterations I made in single player, but am still unable to alter it, open the chests, ...
How come the exact same data works for the same Minecraft.exe runner in a single player world, but does not work when connecting from the same Minecraft.exe runner connected to the multiplayer server? This tells me that the chunk is not really corrupted, or if it is, it is really subtle. Something that only the multiplayer server is bugging on.
My world folder is pretty big, but I could put it on my Google Drive if you'd like it for debugging.