Server error, crashes clients.

As per title. When I login I have a few seconds logged into the world. I can't interact with entities and one chunk is loaded (the one I'm in). After a few seconds I'm kicked out with
io.netty.handler.timeout.ReadTimeoutException

I've already disabled all plugins and mods that deal with chests and stuff like that. Hell, I disabled all the plugins. I don't know what to do.

Below is the detailed stacktrace.

I really hope anybody among you guys can help me!

Update 1: what looks like to me is that I placed a chest where a dropper was before and minecraft didn't like it for some reason. How can I remove such chest?

Code:

17.09 00:26:30 [Server] INFO at net.minecraft.tileentity.TileEntityChest.func_145979_i(TileEntityChest.java:294) ~[ani.class:?]
17.09 00:26:30 [Server] INFO java.lang.ClassCastException: net.minecraft.tileentity.TileEntityDropper cannot be cast to net.minecraft.tileentity.TileEntityChest
17.09 00:26:30 [Server] INFO [00:26:30 ERROR]: Cause of unexpected exception was
17.09 00:26:30 [Server] INFO ... 4 more
17.09 00:26:30 [Server] INFO at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:893) ~[MinecraftServer.class:?]
17.09 00:26:30 [Server] INFO at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:667) ~[mj.class:?]
17.09 00:26:30 [Server] INFO at net.minecraft.world.World.func_72939_s(World.java:2526) ~[afn.class:?]
17.09 00:26:30 [Server] INFO at net.minecraft.tileentity.TileEntityChest.func_145845_h(TileEntityChest.java:334) ~[ani.class:?]
17.09 00:26:30 [Server] INFO at net.minecraft.tileentity.TileEntityChest.func_145979_i(TileEntityChest.java:294) ~[ani.class:?]
17.09 00:26:30 [Server] INFO Caused by: java.lang.ClassCastException: net.minecraft.tileentity.TileEntityDropper cannot be cast to net.minecraft.tileentity.TileEntityChest
17.09 00:26:30 [Server] INFO at java.lang.Thread.run(Unknown Source) [?:1.7.0_51]
17.09 00:26:30 [Server] INFO at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:622) [MinecraftServer.class:?]
17.09 00:26:30 [Server] INFO at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:759) ~[MinecraftServer.class:?]
17.09 00:26:30 [Server] INFO at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:429) ~[lj.class:?]
17.09 00:26:30 [Server] INFO at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:909) ~[MinecraftServer.class:?]
17.09 00:26:30 [Server] INFO net.minecraft.util.ReportedException: Ticking block entity
17.09 00:26:30 [Server] INFO [00:26:30 ERROR]: Encountered an unexpected exception

Update #2.
I wrote a plugin which only purpose was to replace the troubling blocks with cobblestone. For some reason, said blocks weren't affected at all. Here's my code:

Code:

package com.github.blahsd.troubleMover;
 
import org.bukkit.Bukkit;
import org.bukkit.Material;
import org.bukkit.World;
import org.bukkit.plugin.java.JavaPlugin;
 
public class troubleMover extends JavaPlugin {
   
    public void onEnable () {
        World world = Bukkit.getWorlds().get(0);
        world.getBlockAt(11554, 94, 971).setType(Material.COBBLESTONE);
        world.getBlockAt(11554, 95, 971).setType(Material.COBBLESTONE);
        world.getBlockAt(11554, 93, 971).setType(Material.COBBLESTONE);
        world.getBlockAt(11553, 94, 971).setType(Material.COBBLESTONE);
        world.getBlockAt(11555, 94, 971).setType(Material.COBBLESTONE);
        world.getBlockAt(11554, 94, 970).setType(Material.COBBLESTONE);
        world.getBlockAt(11554, 94, 972).setType(Material.COBBLESTONE);
        world.getBlockAt(11554, 94, 973).setType(Material.COBBLESTONE);
    }
}

Update #3.

After I fixed the plugins coordinates, which still weren't affected in the game, I'm now able to log in in a more stable way. Until I try destroying the chest. Then, this:

Code:

17.09 02:32:17 [Server] INFO [02:32:17 INFO]: rfadiga left the game.
17.09 02:32:17 [Disconnect] User [02:32:17 INFO]: rfadiga has disconnected, reason: Internal server error
17.09 02:32:17 [Server] INFO at java.lang.Thread.run(Unknown Source) [?:1.7.0_51]
17.09 02:32:17 [Server] INFO at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:622) [MinecraftServer.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:759) [MinecraftServer.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:429) [lj.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:929) [MinecraftServer.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:173) [ms.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:206) ~[ef.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.network.play.client.C07PacketPlayerDigging.func_148833_a(SourceFile:8) ~[iw.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.network.play.client.C07PacketPlayerDigging.func_148833_a(SourceFile:53) ~[iw.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.network.NetHandlerPlayServer.func_147345_a(NetHandlerPlayServer.java:761) ~[mx.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.server.management.ItemInWorldManager.func_73082_a(ItemInWorldManager.java:274) ~[mn.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.server.management.ItemInWorldManager.func_73084_b(ItemInWorldManager.java:356) ~[mn.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.server.management.ItemInWorldManager.func_73079_d(ItemInWorldManager.java:300) ~[mn.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.block.Block.removedByPlayer(Block.java:1343) ~[ahu.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.world.World.func_147468_f(World.java:966) ~[afn.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.world.World.func_147465_d(World.java:828) ~[afn.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.world.chunk.Chunk.func_150807_a(Chunk.java:626) ~[aoj.class:?]
17.09 02:32:17 [Server] INFO at net.minecraft.block.BlockChest.func_149749_a(BlockChest.java:341) ~[aij.class:?]
17.09 02:32:17 [Server] INFO java.lang.ClassCastException: net.minecraft.tileentity.TileEntityDropper cannot be cast to net.minecraft.tileentity.TileEntityChest
17.09 02:32:17 [Server] INFO [02:32:17 WARN]: Failed to handle packet for /82.60.101.180:65359

Solved.

Switching to CraftBukkit (from Cauldron) allowed the plugin to do its job. I'm now back to Cauldron and everything is great.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.